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Transmission electron microscopy

Transmission electron microscopy (TEM) is a powerful imaging technique that utilizes a beam of electrons transmitted through an ultrathin specimen to produce high-resolution images of internal structures at the nanoscale.^[1] Unlike light microscopy, which is limited by the wavelength of visible light to resolutions around 200 nm, TEM employs electrons with much shorter de Broglie wavelengths, enabling atomic-scale resolution as fine as 0.2 nm or better in modern instruments equipped with aberration correctors.^[2] The process involves accelerating electrons to energies typically between 40 and 300 keV in a vacuum column, focusing the beam with electromagnetic lenses, and detecting transmitted electrons after they interact with the specimen via scattering or diffraction to form contrast in the image.^[1] Developed in the early 1930s by Max Knoll and Ernst Ruska, who built the first transmission electron microscope in 1931 and demonstrated a prototype surpassing light microscope resolution in 1933, TEM became commercially available in 1939 and earned Ruska the Nobel Prize in Physics in 1986 for its foundational development.^[1] TEM operates in various modes, including bright-field imaging for amplitude contrast based on electron density differences, dark-field for scattered electrons highlighting specific features, and high-resolution modes for lattice imaging of crystalline materials.^[1] Specimens must be prepared as thin sections (typically <100 nm thick) through techniques like ultramicrotomy, embedding in resin, or cryogenic freezing to minimize damage from the high-energy electron beam, which can cause beam-induced artifacts in biological samples.^[3] Key applications span materials science for analyzing nanostructures in semiconductors and catalysts, biology for visualizing cellular ultrastructures like viruses and organelles, and nanotechnology for characterizing atomic arrangements and defects.^[1] Advanced variants, such as scanning transmission electron microscopy (STEM), combine raster scanning with detection of transmitted or scattered electrons to provide elemental mapping via energy-dispersive X-ray spectroscopy.^[4] Despite its strengths, TEM requires specialized facilities due to the need for ultra-high vacuum and radiation safety, and sample preparation remains a labor-intensive step limiting throughput.^[3]

History

Early development

The foundational work on transmission electron microscopy (TEM) began with the theoretical and experimental advancements in electron optics during the late 1920s. In 1927, German physicist Hans Busch demonstrated that magnetic fields could focus electron beams, inventing the magnetic lens by calculating electron trajectories in axially symmetric fields, which laid the groundwork for electron microscopy.^[5] This breakthrough, detailed in Busch's seminal paper, enabled the manipulation of electrons analogous to light through optical lenses. Building on Busch's principles, Ernst Ruska, then a graduate student at the Technical University of Berlin, collaborated with his advisor Max Knoll to construct the first TEM prototype in 1931. This instrument used two magnetic lenses and produced the first electron micrograph, magnifying a platinum grid by about 400 times, though it did not yet surpass the resolving power of light microscopes.^[6] By 1933, Ruska, working independently, refined the design with improved pole-piece lenses, creating the first practical TEM that exceeded the ~200 nm limit of optical microscopes and a magnification up to 12,000 times.^[7] This 1933 model marked the birth of TEM as a viable imaging tool for ultrastructural studies. Commercialization accelerated in the late 1930s through Ruska's partnership with Bodo von Borries at Siemens & Halske. In 1939, the company introduced the first commercial TEM, the Siemens Supersmikroskop, with a resolution of about 10 nm, enabling broader scientific adoption despite the onset of World War II.^[8] Wartime efforts in Germany focused on refining production at Siemens amid resource constraints, while in the United States, RCA Laboratories independently developed their first TEM prototype around 1940, spurred by military interests in materials analysis.^[9] These parallel advancements ensured TEM's survival and growth into the postwar era. For his pioneering contributions, Ruska shared the 1986 Nobel Prize in Physics with Gerd Binnig and Heinrich Rohrer.^[10]

Resolution improvements

During the mid-20th century, significant hardware advancements in transmission electron microscopy (TEM) focused on mitigating lens aberrations and enhancing beam quality to push resolution limits. In the 1960s, the introduction of high-voltage TEM instruments, such as Hitachi's 1 MeV models developed by 1966, reduced chromatic aberration by accelerating electrons to higher energies, minimizing the impact of energy spread on focusing and enabling imaging of thicker specimens with improved clarity. These systems, operating at voltages exceeding 500 kV, also lessened beam scattering, allowing resolutions approaching 0.3 nm for lattice imaging in materials.^[11]^[12] The development of field emission guns (FEGs) in the late 1960s further revolutionized beam characteristics. Hitachi initiated FEG research in 1969, producing stable, high-brightness electron sources that offered superior coherence and reduced energy spread compared to thermionic guns, thereby enhancing spatial resolution to below 0.5 nm and supporting atomic-scale contrast in both conventional TEM and scanning TEM (STEM) modes. Pioneering work by Albert Crewe at the University of Chicago integrated FEGs into STEM instruments by the early 1970s, achieving single-atom imaging with resolutions around 0.2 nm and introducing Z-contrast mechanisms for compositional mapping, which broke previous barriers in solid-state structure visualization.^[13]^[14] In the 1970s, refinements to objective apertures and awareness of Laue zone effects optimized contrast mechanisms in high-resolution TEM. Smaller apertures selectively filtered diffracted beams to suppress unwanted scattering while preserving phase contrast, improving image interpretability for defect analysis and lattice fringes down to 0.2 nm, as demonstrated in early STEM prototypes. Japanese researcher Hatsujiro Hashimoto contributed key advancements in high-resolution imaging techniques during this era, including through-focal series methods and in-situ observations that clarified atomic arrangements in crystals, laying groundwork for quantitative structural studies.^[15] The 1980s marked the transition to digital imaging with the integration of charge-coupled device (CCD) detectors into TEM systems, first reported around 1982 and widely adopted by the decade's end. These detectors provided higher dynamic range and faster acquisition than photographic film, enabling noise-reduced images at sub-0.2 nm resolutions and facilitating computational processing for enhanced contrast and alignment in high-resolution datasets. This shift supported broader applications in materials science, where quantitative metrics like fringe spacing could be reliably measured.^[16]

Modern advancements

In the early 2000s, the implementation of aberration correction revolutionized transmission electron microscopy (TEM) by compensating for spherical and chromatic aberrations in electron lenses, enabling sub-0.1 nm resolution. A seminal advancement was the development of a sextupole-based corrector by Nion Co., which was integrated into a scanning TEM (STEM) and demonstrated sub-Ångström resolution in 2002, allowing direct imaging of atomic columns in materials like silicon. This corrector design, using hexapole and quadrupole elements to introduce negative spherical aberration, overcame longstanding limitations in probe-forming apertures and marked a shift toward atomic-scale analytical capabilities. The commercialization of aberration-corrected TEMs accelerated in the 2010s, with major manufacturers like JEOL and Hitachi incorporating corrector technology into production instruments, making sub-0.1 nm resolution accessible beyond specialized labs. By mid-decade, over 200 such systems had been installed globally, facilitating widespread applications in materials science, such as precise mapping of dopant distributions in semiconductors. This era's hardware integration, building on Nion's pioneering correctors, enhanced signal-to-noise ratios and enabled simultaneous imaging and spectroscopy at atomic resolution.^[17] The 2010s also saw the rise of four-dimensional scanning transmission electron microscopy (4D-STEM), which records a full diffraction pattern at each scan position using pixelated detectors, providing momentum-resolved information for advanced phase and strain mapping. Enabled by fast direct electron detectors like those developed around 2011, 4D-STEM allowed reconstruction of local crystal orientations and electric fields with sub-nanometer precision, as demonstrated in studies of defects in 2D materials. This technique expanded TEM's scope to include virtual imaging modes, such as center-of-mass analysis for ptychographic phase retrieval, without requiring dedicated hardware upgrades.^[18] By the 2020s, artificial intelligence (AI) integration transformed TEM data processing, particularly for image reconstruction and noise reduction in low-dose scenarios. Deep convolutional neural networks (CNNs), trained on simulated and experimental datasets, achieved superior denoising performance, improving peak signal-to-noise ratios by up to 12 dB in nanoparticle imaging compared to traditional filters. Self-supervised frameworks like SHINE further enabled high-throughput analysis of beam-sensitive samples, automating defect detection and enhancing resolution in cryo-TEM workflows. These AI methods, leveraging generative models, preserved structural details while mitigating Poisson noise inherent to electron counting. In 2024-2025, advancements in direct electron detectors and ptychographic algorithms continued to push low-dose imaging capabilities, achieving sub-Ångström resolutions in beam-sensitive materials.^[19]^[20] A key event in 2023 was the advancement in electron ptychography for robust phase retrieval, where iterative algorithms reconstructed high-fidelity phase maps from 4D-STEM datasets, achieving super-resolution beyond the probe size. Techniques like those applied to low-dimensional materials recovered spatial frequencies up to 2 Å, enabling quantitative visualization of light elements and lattice distortions in radiation-sensitive specimens. This progress, supported by optimized scanning parameters, bridged the gap between conventional STEM and holographic methods for artifact-free phase contrast.^[21] Post-2020 trends include the development of ultrafast laser-pumped TEM for capturing dynamic processes on picosecond timescales, combining laser excitation with stroboscopic electron probing. Instruments like JEOL's Luminary system synchronize femtosecond laser pulses with electron bunches to image photo-induced phase transitions in nanomaterials, achieving spatiotemporal resolution of ~100 fs and ~1 nm. This hybrid approach has revealed transient phenomena, such as exciton dynamics in 2D semiconductors, expanding TEM to time-resolved studies of non-equilibrium states.^[22]

Fundamental principles

Electron interactions with matter

In transmission electron microscopy (TEM), the incident high-energy electrons interact with the atoms in the specimen primarily through scattering processes, which form the basis for image formation and spectroscopic analysis. These interactions occur over a limited volume due to the strong Coulomb forces between the fast-moving electrons and the atomic nuclei and electrons in the sample. The nature of these interactions—elastic or inelastic—determines whether the electron retains its energy or loses some to the specimen, influencing the transmitted beam's properties. Elastic scattering involves no significant energy loss by the incident electron, with the deflection resulting from the electrostatic interaction with the atomic nucleus or orbital electrons; this process is dominant for small-angle scattering and is described by Rutherford scattering theory for unscreened Coulomb potentials. The differential cross-section for elastic scattering follows the form

\frac{d\sigma}{d\Omega} \propto \frac{Z^2}{\sin^4(\theta/2)},

where Z is the atomic number of the scatterer and \theta is the scattering angle, highlighting the strong dependence on atomic number and the forward-peaked nature of scattering at high energies typical in TEM (e.g., 100–300 keV).^[23] In practice, screening effects from atomic electrons modify this for low angles, but the Rutherford form approximates high-angle elastic events well, as used in annular dark-field imaging.^[24] In contrast, inelastic scattering involves energy transfer from the incident electron to the specimen, typically ranging from a few eV to thousands of eV, leading to excitations or ionizations; this process contributes to beam attenuation and signal generation in techniques like electron energy-loss spectroscopy (EELS). Key mechanisms include plasmon excitation, where the incident electron collectively excites valence electrons, producing energy losses around 10–30 eV depending on the material, and inner-shell ionization, which ejects a core electron and creates characteristic X-ray emission or Auger electrons for elemental analysis. These inelastic events occur with lower probability than elastic ones but are crucial for contrast in thick specimens and for probing material composition.^[25] The extent of these interactions is characterized by the interaction volume and the mean free path, which defines the average distance an electron travels before undergoing a scattering event; for inelastic scattering, this is approximately 100 nm for 100 keV electrons in carbon, a common reference material in TEM.^[26] The interaction volume is thus on the order of tens to hundreds of nanometers, depending on specimen thickness and electron energy, limiting resolution in thicker samples due to multiple scattering. Monte Carlo simulations model these electron trajectories by statistically sampling scattering events based on cross-sections, enabling prediction of beam spreading, signal collection efficiency, and optimal imaging parameters in complex specimens.^[27] Scattering cross-sections vary significantly between material types: biological specimens, composed mainly of low-Z elements like C, N, O (Z ≈ 6–8), exhibit smaller elastic and inelastic cross-sections compared to inorganic materials with higher Z (e.g., metals like Al, Z=13, or Si, Z=14), resulting in weaker scattering and lower contrast without staining in organics.^[25] These interactions ultimately underpin contrast mechanisms in TEM imaging, such as mass-thickness contrast from beam attenuation.

Electromagnetic lenses and optics

In transmission electron microscopy (TEM), electromagnetic lenses are essential for focusing and manipulating the electron beam, exploiting the interaction between charged particles and magnetic fields. Unlike light optics, where glass lenses refract photons, electron lenses use magnetic fields generated by current-carrying coils to deflect electrons via the Lorentz force. The force acting on an electron with charge -e and velocity \mathbf{v} in a magnetic field \mathbf{B} is given by \mathbf{F} = -e (\mathbf{v} \times \mathbf{B}), which causes the electron's path to curve perpendicular to both \mathbf{v} and \mathbf{B}, enabling convergence or divergence analogous to optical refraction.^[28] This deflection arises because electrons, as de Broglie waves, follow classical trajectories in paraxial approximations while exhibiting wave-like interference in imaging.^[29] The focal length f of a magnetic lens determines its focusing power and depends on the accelerating voltage V, lens current I, number of coil turns N, and magnetic permeability \mu_0. An approximate expression for strong lenses scales as f \propto V / (I N)^2, reflecting that higher voltage increases electron speed and reduces deflection, while stronger currents and more turns enhance the field strength.^[30] In practice, this allows precise control: for typical TEM objective lenses at 200 kV, focal lengths range from 1–5 mm, balancing resolution and working distance. However, imperfections limit performance; spherical aberration, quantified by the coefficient C_s, causes off-axis electrons to focus differently, producing a blur \delta_s \propto r^3 where r is the beam radius, as marginal rays deviate more than paraxial ones.^[31] Similarly, chromatic aberration, with coefficient C_c, arises from energy spread \Delta E in the beam, yielding a focus shift \delta_c \propto \Delta E / E where E is the mean energy, since slower electrons experience stronger deflection.^[32] These aberrations scale with aperture angle and are typically on the order of the focal length for uncorrected lenses, degrading resolution to ~0.2 nm without mitigation.^[33] TEM instruments employ a series of electromagnetic lenses in specific configurations to shape the beam and form images. Condenser lenses, usually two in tandem, demagnify the electron source and control illumination intensity and convergence on the specimen, with the first partially demagnetizing the beam for uniform probing. The objective lens, closest to the specimen, forms the initial diffraction pattern or image with a short focal length (~2 mm) to achieve high magnification (~100x) while minimizing aberrations from proximity. Projector lenses, often two or three, subsequently enlarge and project this intermediate image onto the detector, enabling further magnification up to 1,000,000x.^[34] These lenses are symmetrically designed with iron pole pieces to confine fields, ensuring axial symmetry for rotationally invariant optics.^[35] A fundamental principle governing these systems is the reciprocity theorem in electron optics, which states that the properties of rays traced from object to image are identical to those traced in reverse, implying equivalence between object-plane and image-plane characteristics for a given lens field. This symmetry, derived from the reversibility of Lorentz force trajectories, underpins the equivalence of conventional TEM and scanning TEM imaging modes, allowing identical resolution limits under reciprocal conditions.^[36]^[37]

Image formation and contrast mechanisms

In transmission electron microscopy (TEM), images are formed by collecting electrons that pass through an ultrathin specimen and are subsequently focused by electromagnetic lenses onto a detector, where variations in electron intensity create the visible contrast. The primary interactions responsible for this contrast arise from elastic and inelastic scattering events within the specimen, which modulate the amplitude and phase of the transmitted electron wave.^[38] Contrast in TEM images primarily originates from two mechanisms: amplitude contrast and phase contrast. Amplitude contrast results from the reduction in the intensity of the transmitted electron beam due to absorption or scattering, where electrons are either removed from the direct beam or scattered beyond the acceptance angle of the objective aperture. A key form of amplitude contrast is mass-thickness contrast, which occurs when variations in the specimen's mass density or thickness lead to differential scattering; thicker or denser regions scatter more electrons away from the optic axis, appearing darker in the image due to lower transmitted intensity. This mechanism is particularly prominent in unstained biological samples or amorphous materials, where it provides basic morphological information without relying on phase effects.^[34] Phase contrast, dominant in weakly scattering specimens such as lightly stained biological tissues or thin crystals, arises from the phase shift imparted to the electron wave by the specimen's electrostatic potential, rather than amplitude changes. For thin specimens where multiple scattering is negligible, the weak phase object approximation simplifies the exit wavefunction: the phase shift \phi(\mathbf{r}) \approx \sigma t \int V(z) \, dz, where \sigma is the relativistic electron interaction constant (approximately $7.3 \times 10^{6} \, \mathrm{m/V} at 200 kV), t is the specimen thickness, and V(z) is the projected mean inner potential along the beam direction.^[39] This approximation assumes the transmitted wave amplitude remains nearly unchanged, allowing the phase modulation to be treated linearly. To convert these phase shifts into detectable intensity variations, the objective lens is typically defocused, introducing a quadratic phase shift that interferes with the specimen-induced phase, thereby generating contrast. The optimal defocus for enhancing phase contrast while minimizing spherical aberration effects is the Scherzer defocus, given by \Delta f = -1.2 \sqrt{C_s \lambda}, where C_s is the spherical aberration coefficient and \lambda is the electron wavelength; this condition ensures a positive contrast transfer up to the Scherzer resolution limit d_s \approx 0.66 (C_s \lambda^3)^{1/4}.^[40]^[41]^[42] The overall image formation is governed by the contrast transfer function (CTF), which describes how the microscope modulates the spatial frequencies of the specimen's projected potential in the final image. Under the weak phase object approximation and paraxial ray optics, the CTF for defocus \Delta f and spherical aberration C_s is \mathrm{CTF}(k) = \sin\left[ -\frac{\pi}{2} (C_s \lambda^3 k^4 + \Delta f \lambda k^2) \right], where k is the spatial frequency; the envelope of this function is damped by additional aberrations (e.g., chromatic) and partial coherence, limiting the transferable frequencies. The fundamental diffraction-limited resolution follows the Rayleigh criterion adapted for electrons: d = 0.61 \lambda / \alpha, where \alpha is the objective aperture semi-angle (analogous to the numerical aperture); for 200 kV electrons (\lambda \approx 2.5 \, \mathrm{pm}) and \alpha \approx 10 \, \mathrm{mrad}, this yields d \approx 0.15 \, \mathrm{nm}, though aberrations typically reduce the practical resolution to 0.2 nm or better in corrected instruments.^[43]^[2]

Instrument components

Electron source

The electron source in transmission electron microscopy (TEM) generates a focused beam of electrons that serves as the illumination for imaging thin specimens. Early TEM instruments, developed in the 1930s, relied on thermionic emission from tungsten filaments, but over time, there has been a progressive shift toward brighter and more stable sources to enhance resolution and signal-to-noise ratios. This evolution includes the adoption of lanthanum hexaboride (LaB₆) cathodes in the 1970s for improved performance over tungsten, followed by field emission guns (FEGs) in the late 20th century, with modern instruments favoring cold FEGs for their superior beam characteristics.^[44] Thermionic sources produce electrons by heating a cathode material until thermal energy exceeds the work function, allowing electrons to escape into vacuum. Tungsten hairpin filaments, the original choice heated to about 2800 K, offer a beam brightness of approximately 10⁵ A/cm² sr but suffer from a relatively broad energy spread of 1–3 eV, governed by the Maxwell-Boltzmann distribution and roughly on the order of kT (where k is Boltzmann's constant and T is temperature). LaB₆ cathodes, introduced as an upgrade due to their lower work function of 2.7 eV, operate at reduced temperatures around 1700–1800 K, achieving brightness levels of ~10⁶ A/cm² sr—about 10 times higher than tungsten—while maintaining a similar energy spread of ~1–2 eV and providing longer operational lifetimes of up to several thousand hours. These sources are valued for their simplicity and robustness in routine TEM applications.^[45]^[46]^[47] Field emission sources extract electrons via quantum tunneling under a strong electric field applied to a sharply pointed cathode, yielding dramatically higher brightness and narrower energy spreads compared to thermionic types. Schottky emitters, which combine field emission with mild thermal assistance (heating a zirconium oxide-coated tungsten tip to ~1800 K), deliver brightness of ~10⁸ A/cm² sr and energy spreads below 1 eV, enabling finer probe sizes and better coherence for high-resolution imaging. Cold FEGs, operating at room temperature without heating, further reduce energy spread to <0.5 eV and can achieve even higher brightness, though they require ultra-high vacuum to prevent tip contamination. The pioneering work on field emission sources by Albert Crewe in 1968 revolutionized TEM by enabling atomic-scale resolution through these enhanced beam properties.^[48]^[47] In the electron gun, emitted electrons are initially extracted using voltages of several kilovolts and then accelerated by an anode to final energies of 100–300 keV, forming a collimated beam with controlled divergence. This acceleration stage, often designed as a triode or tetrode configuration, optimizes beam current and stability while minimizing aberrations at the source. The choice of source directly impacts beam brightness and energy spread, which in turn set the limits for spatial resolution and contrast in downstream TEM optics.^[49]

Lenses and apertures

In transmission electron microscopy (TEM), lenses and apertures are essential optical elements that shape, focus, and filter the electron beam to form high-quality images. Electromagnetic lenses, primarily the objective and condenser lenses, manipulate the electron trajectories, while apertures control beam intensity, contrast, and resolution by selectively blocking off-axis or scattered electrons. These components must be precisely aligned to minimize distortions and aberrations, ensuring the beam illuminates the specimen uniformly and the resulting image accurately represents the sample structure.^[50] The objective aperture, positioned in the back focal plane of the objective lens, plays a critical role in contrast selection by intercepting scattered electrons beyond a defined angular range, thereby enhancing image visibility in bright-field mode. Typical objective apertures have diameters ranging from 10 to 100 μm, allowing operators to adjust contrast levels—smaller apertures increase contrast by excluding more diffracted beams but may reduce signal intensity, while larger ones permit broader beam collection for higher resolution imaging. This selective filtering improves the signal-to-noise ratio, particularly for weakly scattering specimens like biological samples.^[51]^[52]^[53] Condenser apertures, located within the illumination system upstream of the specimen, regulate beam current and convergence angle to optimize specimen illumination without excessive damage. The second condenser (C2) aperture, for instance, limits the fraction of electrons from the condenser lens crossover that reaches the sample, controlling probe size and intensity; smaller apertures reduce beam current to prevent specimen heating or charging, while larger ones allow higher currents for analytical techniques like energy-dispersive X-ray spectroscopy. This control is vital for balancing resolution and throughput in imaging sessions.^[50]^[54] Lens alignment is achieved through deflection coils and stigmators, which correct off-axis aberrations and astigmatism to maintain beam circularity and focus. Stigmators introduce adjustable quadrupole fields to compensate for magnetic field asymmetries in the lenses, ensuring a symmetric beam profile; for example, objective lens astigmatism is minimized by iteratively adjusting stigmator currents until the focal spot appears round under slight defocus. Proper alignment is essential for high-resolution imaging, as uncorrected astigmatism can distort lattice fringes or broaden point spread functions.^[55]^[56] In uncorrected TEM instruments, practical spherical aberration coefficients (Cs) for objective lenses typically measure around 1 mm, limiting the interpretable resolution to approximately 0.2 nm at 100-200 kV accelerating voltages due to off-axis ray defocusing. This value sets the Scherzer defocus condition for optimal phase contrast, where the lens is operated under negative spherical aberration to extend the coherent transfer function.^[57]^[58] Aperture-related artifacts, such as halos surrounding features in phase contrast images, arise from chromatic effects where electrons with varying energies (due to source spread or plasmon losses) are differentially focused by the objective aperture. These halos manifest as bright or dark rings around high-contrast edges, degrading interpretability, and are exacerbated in thicker specimens or with energy spreads exceeding 1 eV; mitigation often involves energy filtering or aberration correction to narrow the effective energy window.^[59]^[60]

Specimen stage and vacuum system

The specimen stage and vacuum system in a transmission electron microscope (TEM) are essential for maintaining the integrity of the electron beam and the sample during imaging. The vacuum system ensures that residual gas molecules do not scatter the electrons, which would degrade image quality and resolution. Typical operating pressures in the microscope column range from 10^{-5} to 10^{-7} Pa, while the electron gun requires ultra-high vacuum levels of 10^{-7} to 10^{-10} Pa to minimize interactions with gas molecules and prevent arcing or contamination of the source.^[61]^[62] These low pressures extend the mean free path of electrons to exceed the length of the microscope column, typically several meters, thereby supporting high beam stability essential for atomic-scale imaging.^[34] To achieve these vacuum levels, TEMs employ a combination of pumps, including roughing pumps for initial evacuation from atmospheric pressure to about 1 Pa, followed by turbomolecular or diffusion pumps for high vacuum in the column, and ion pumps for ultra-high vacuum in the gun region.^[34] Differential pumping is a critical feature that isolates regions of differing vacuum requirements; small apertures separate the gun chamber, maintained at higher vacuum by dedicated ion pumps, from the main column, preventing gas diffusion that could compromise the electron source while allowing the specimen area to operate at slightly higher pressures compatible with sample introduction.^[34]^[63] This staged approach ensures overall system reliability without necessitating the entire instrument to reach the stringent vacuum of the gun. The specimen stage, often a goniometer, enables precise manipulation of the sample to optimize orientation for imaging or diffraction studies. Standard double-tilt goniometers provide tilt ranges of ±60° about the X-axis and ±30° about the Y-axis, allowing alignment of crystalline features or collection of tilt series for tomography while keeping the specimen near the eucentric height—the optical axis intersection point.^[64]^[65] Piezoelectric actuators are commonly integrated for fine eucentricity adjustments, compensating for mechanical drift and ensuring the sample remains in focus during tilts with sub-micrometer precision.^[64] Specialized specimen holders for many TEM stages provide temperature control to mitigate beam-induced damage or phase changes in sensitive specimens. Cooling capabilities, often via liquid nitrogen or Peltier elements, can reach down to -196°C with liquid nitrogen or -30°C with Peltier, while heating functions extend up to 100°C or higher using resistive elements, providing controlled environments for observing subtle structural variations without specialized holders.^[66]^[67] These features enhance specimen stability under the electron beam, indirectly supporting consistent imaging conditions.

Detectors and display

In the early development of transmission electron microscopy (TEM), electrons transmitted through the specimen were initially detected using fluorescent screens, which converted the electron beam into visible light for direct observation by the microscopist. These screens, typically coated with phosphors such as zinc sulfide, provided real-time imaging but suffered from low efficiency and required dark adaptation due to the dim output. Photographic plates, often emulsion-based films like Kodak SO-163, served as the primary recording medium, capturing high-resolution images through direct exposure to electrons, though they demanded long exposure times and chemical processing.^[68] Modern TEM instruments predominantly employ charge-coupled device (CCD) and complementary metal-oxide-semiconductor (CMOS) cameras for electron detection, which indirectly record the signal by first converting electrons to light via a scintillator and then to electrical charges in the sensor array.^[69] These cameras feature pixel sizes typically ranging from 10 to 20 μm, enabling sufficient sampling of the electron beam's spatial distribution while maintaining compatibility with TEM magnification scales.^[70] Their dynamic range exceeds 10^4 (often achieving 14-bit depth or 16,384 levels), allowing capture of both low-intensity features and high-contrast details without saturation.^[71] For applications requiring minimal electron dose, such as imaging beam-sensitive biological samples, direct electron detectors like the Medipix hybrid pixel detector and the K2 Summit have become essential, as they count individual electrons without intermediate light conversion, reducing noise and enabling super-resolution capabilities.^[68] The Medipix, with its silicon pixel array, achieves single-electron sensitivity through charge integration and thresholding, ideal for low-dose regimes where electron flux is below 1 electron per pixel per frame.^[72] Similarly, the K2 Summit, a monolithic active pixel sensor, supports electron counting at frame rates up to 40 Hz, facilitating dose fractionation in cryo-EM to mitigate specimen damage while preserving signal-to-noise ratio.^[73] Post-detection signal processing enhances image quality through techniques such as binning, which combines adjacent pixels to reduce readout noise and increase effective sensitivity at the cost of spatial resolution; gain control, which adjusts amplification to optimize the electron-to-digital signal conversion; and digital magnification, which interpolates pixel data for zoomed views without altering the physical optics.^[74] These processes are typically implemented in real-time via dedicated hardware and software, allowing for immediate feedback during experiments. The performance of these detectors is quantified using detective quantum efficiency (DQE), a metric that assesses how effectively the device preserves signal-to-noise ratio from incident electrons, with modern direct detectors routinely achieving DQE values greater than 0.5 across relevant spatial frequencies, far surpassing earlier CCD systems.^[75] This high DQE ensures that contrast generated by upstream optics is faithfully represented in the final image, minimizing information loss.^[68]

Imaging and analytical techniques

Bright-field and diffraction imaging

In transmission electron microscopy (TEM), bright-field imaging employs the central, undiffracted electron beam aligned along the optic axis to form images, where contrast arises primarily from amplitude differences due to mass-thickness variations in the specimen; thicker or higher-density regions scatter more electrons, appearing darker against a brighter background of directly transmitted electrons.^[76] This mode provides straightforward visualization of specimen morphology and density gradients, with the objective aperture typically blocking scattered electrons to enhance contrast.^[77] Dark-field imaging, in contrast, selects off-axis diffracted or inelastically scattered electrons using a displaced objective aperture or by tilting the incident beam, highlighting regions where scattering occurs, such as crystalline defects or heavy elements, while unscattered areas appear dark.^[77] This technique excels at revealing subtle structural features invisible in bright-field, like strain fields around dislocations, by exploiting diffraction contrast mechanisms described in early kinematical theories.^[77] Diffraction imaging in TEM often involves switching to diffraction mode, where the selected area aperture—typically with diameters ranging from 0.5 to 2 μm—is inserted into the intermediate image plane to isolate electrons from a specific specimen region, producing spot or ring patterns that reveal local crystal structure and orientation.^[78] Kikuchi patterns, arising from inelastic scattering and Bragg diffraction in thicker crystals, manifest as paired lines and bands in these patterns, enabling precise determination of crystal orientation by indexing the intersections with known lattice planes.^[79] A key application of these modes is the imaging of dislocations in crystalline materials, where bright-field reveals overall contrast from lattice distortions, while dark-field under two-beam conditions highlights individual dislocation lines as bright segments against a dark background, facilitating quantitative analysis of defect density and Burgers vectors.^[80] Pioneering observations in metals like aluminum demonstrated this capability, establishing TEM as essential for understanding plastic deformation mechanisms.^[80]

Phase contrast and high-resolution imaging

Phase contrast imaging in transmission electron microscopy (TEM) leverages the phase shifts induced by a specimen's electrostatic potential on the electron wave to achieve high-resolution visualization of weakly scattering objects, such as light atoms in biological or amorphous materials, where amplitude contrast is insufficient.^[81] In conventional TEM, phase contrast arises from defocusing the objective lens, which converts phase variations into detectable intensity modulations via the contrast transfer function (CTF). This approach enables the imaging of lattice fringes and atomic structures by balancing spherical aberration and defocus effects.^[42] Defocus phase contrast is optimized at the Scherzer defocus condition, where the negative defocus \Delta f = -1.2 (C_s \lambda^3)^{1/4} (with C_s as the spherical aberration coefficient and \lambda as the electron wavelength) maximizes phase contrast transfer for weak-phase objects while minimizing delocalization.^[42] This setting achieves the Scherzer resolution limit of d = 0.66 (C_s \lambda^3)^{1/4}, allowing interpretable imaging of features down to the atomic scale without reversal of contrast in the passband.^[81] For example, in a 200 kV TEM with C_s = 1 mm, this yields \Delta f \approx -11 nm and a resolution of about 0.19 nm.^[42] An alternative to defocus-based methods is Z-contrast imaging using high-angle annular dark-field (HAADF) detection in scanning TEM (STEM) mode, which provides incoherent imaging proportional to the square of the atomic number (Z) for compositional mapping at atomic resolution.^[82] This technique, developed by Pennycook and coworkers, collects Rutherford-scattered electrons to produce bright spots from heavy atoms while minimizing diffraction effects, enabling direct interpretation of atomic columns without phase retrieval.^[82] Quantitative analysis of HAADF intensities allows column-by-column composition determination, as demonstrated in aberration-corrected STEM for alloys and nanostructures.^[83] To overcome limitations of single-defocus images, such as CTF-induced contrast oscillations, exit-wave reconstruction from a focal series of TEM images recovers the full complex specimen exit wave, including both amplitude and phase information.^[84] This iterative algorithm, pioneered by Coene et al., propagates the recorded images through focus to iteratively refine the exit wave while correcting for aberrations.^[85] Typically, 10-20 images spaced by 5-10 nm in defocus are sufficient for atomic-scale reconstruction, enhancing interpretability for beam-sensitive materials.^[84] High-resolution phase contrast has enabled atomic imaging in materials like graphene, where aberration-corrected TEM enables imaging of the graphene lattice with resolutions approaching 0.05 nm, revealing defects and strain with sub-angstrom precision.^[86] For CTF calibration in such experiments, diffractogram analysis of the image's Fourier transform produces Thon rings—oscillatory patterns whose envelope and periodicity fit defocus and C_s values accurately.^[87] This method ensures reliable phase contrast by verifying the microscope's transfer function against known standards.^[87]

Electron diffraction and crystallography

Electron diffraction in transmission electron microscopy (TEM) enables the determination of crystal structures by analyzing the scattering of electrons from atomic planes, providing reciprocal space information complementary to real-space imaging. This technique relies on the wave nature of electrons, where the de Broglie wavelength \lambda is given by \lambda = \frac{h}{\sqrt{2 m e V}}, with h as Planck's constant, m the electron mass, e the elementary charge, and V the accelerating voltage, typically yielding \lambda \approx 0.002 nm at 200 kV for atomic-scale resolution. Diffraction occurs when electrons satisfy Bragg's law, $2 d \sin \theta = n \lambda, where d is the interplanar spacing, \theta the Bragg angle, n an integer, and \lambda the electron wavelength, allowing measurement of lattice parameters from observed diffraction spots. This pattern-based approach reveals crystal symmetry and orientation, distinct from image contrast mechanisms like diffraction contrast, where variations in intensity arise from dynamical scattering effects. Convergent beam electron diffraction (CBED) enhances structural analysis by illuminating a small specimen area (~10-50 nm) with a focused, convergent electron beam, producing disk-like diffraction patterns with higher-order Laue zone (HOLZ) lines that encode three-dimensional symmetry information. CBED is particularly valuable for determining point group symmetry, space group, and lattice strain at the nanoscale, as the overlapping disks exhibit intensity variations sensitive to crystal thickness and orientation. For instance, symmetry breaking in the central disk or HOLZ patterns can distinguish between space groups differing only in glide planes or screw axes. The technique's sensitivity to strain arises from shifts in HOLZ line positions, enabling quantitative mapping of local deformations with sub-percent accuracy. Precession electron diffraction (PED) extends CBED by rocking the incident beam around the optical axis at a small precession angle (typically 1-3°), which reduces dynamical scattering effects and samples a larger volume of three-dimensional reciprocal space more uniformly. This method generates quasi-kinematical patterns, improving the accuracy of intensity measurements for structure factor refinement and phase identification, while the precession motion sweeps the Ewald sphere to capture multiple zone axes in a single tilt series. PED is especially useful for beam-sensitive materials, as it distributes the electron dose, minimizing damage during data collection. Indexing of electron diffraction patterns involves assigning Miller indices (hkl) to observed spots to identify the crystal structure and orientation, often using algorithms that match experimental inter-spot distances and angles to simulated patterns from known or candidate structures. Common methods include the ratio method, which computes angles between spots to determine the zone axis [uvw] by solving for the direction perpendicular to the diffraction plane, or dictionary-based approaches that compare patterns against a database for automated matching. Zone axis determination is critical for aligning the beam parallel to a low-index direction, facilitating systematic absences analysis for space group assignment; software like ASTAR or RAPID implements these algorithms, achieving indexing success rates over 90% for cubic and hexagonal systems. Accurate indexing requires calibration of the camera length and correction for lens astigmatism to ensure precise d-spacing measurements. In nanomaterials, electron diffraction via TEM is widely applied for phase identification, where selected area or nanobeam patterns reveal polymorphic phases in heterogeneous samples, such as distinguishing anatase from rutile in TiO₂ nanoparticles by unique spot spacings. This capability is essential for understanding structure-property relationships in alloys, perovskites, and quantum dots, enabling rapid verification of synthesis outcomes without bulk averaging. For example, CBED and PED have identified minor phases in catalytic nanomaterials, correlating local crystallography with enhanced reactivity.

Spectroscopy and tomography

Transmission electron microscopy (TEM) incorporates spectroscopic techniques to analyze elemental composition and chemical bonding at the nanoscale by measuring energy losses of transmitted electrons. Electron energy loss spectroscopy (EELS) is a primary method, where core-loss edges in the spectrum correspond to inner-shell ionizations, enabling elemental identification and mapping. For instance, L-edges of transition metals, such as those in iron or cobalt, provide characteristic signals around 700-800 eV, allowing quantitative analysis with ionization cross-sections typically on the order of 10 barns.^[88]^[89] Energy-filtered TEM (EFTEM) extends EELS by enabling parallel acquisition of elemental maps across the entire field of view, improving efficiency for large-area analysis. In EFTEM, a magnetic prism or omega filter selects electrons within a narrow energy window post-specimen, producing images filtered at specific core-loss edges for direct visualization of element distribution. This approach achieves spatial resolutions down to ~1 nm for light elements, surpassing sequential scanning methods in speed while maintaining high signal-to-noise ratios.^[90]^[91] Four-dimensional scanning TEM (4D-STEM) advances momentum-resolved spectroscopy by recording full diffraction patterns at each scan position, yielding a 4D dataset that captures both spatial and reciprocal space information. This technique facilitates ptychographic reconstruction and center-of-mass analysis for phase and strain mapping, with applications in probing local electronic structure via convergent beam electron diffraction patterns. By integrating EELS with 4D-STEM, momentum-dependent energy losses can be mapped, enhancing sensitivity to bonding and valence states.^[18] Tomography in TEM reconstructs three-dimensional structures from a tilt series of 2D projections, typically acquired over ±60-70° to minimize the missing wedge artifact. Reconstruction employs filtered back-projection algorithms, which apply a ramp filter to projections before back-projecting to form the 3D volume, achieving resolutions around 1 nm for densely tilted series in materials science. This method reveals internal architectures, such as nanoparticle distributions or defect networks, with quantitative density mapping when combined with spectroscopic data.^[92]^[93] Dose management is critical in these techniques to prevent beam-induced damage, guided by the Rose criterion requiring a signal-to-noise ratio (SNR) greater than 5 for reliable feature detection. In EELS and tomography, low-dose strategies limit electron exposure to ~10-100 e/Å² per projection, balancing SNR with specimen integrity, particularly for beam-sensitive samples like organics or perovskites. Alignment via electron diffraction patterns ensures accurate tilt-series registration without excessive dosing.^[94]^[95]

Sample preparation

Biological sample preparation

Biological samples for transmission electron microscopy (TEM) must be prepared as ultrathin sections or films, typically less than 100 nm thick, to allow electron transmission while preserving native structures and ensuring compatibility with the instrument's high vacuum environment. Traditional preparation involves chemical fixation to stabilize cellular components, followed by dehydration, embedding in resin, and sectioning, whereas cryogenic methods aim to vitrify water in the sample to avoid ice crystal damage. These approaches enable visualization of subcellular details, such as organelles and macromolecular complexes, but require careful handling to minimize artifacts like structural distortion.^[96] Ultramicrotomy is a key technique for producing thin sections of resin-embedded biological specimens, using an ultramicrotome equipped with a diamond knife to achieve slices of 50-100 nm thickness. The process begins with trimming the embedded block to expose a flat face, followed by aligning it parallel to the knife edge in a water-filled boat to collect floating sections onto grids. Diamond knives are preferred over glass due to their durability and ability to produce smoother cuts with reduced chatter, enabling serial sectioning for three-dimensional reconstruction.^[97]^[98]^[99] Negative staining provides rapid contrast enhancement for isolated biological macromolecules or viruses in suspension, without the need for embedding or sectioning. In this method, a heavy metal salt such as 1-2% uranyl acetate is applied to the sample on a grid, where it surrounds the specimen to create a dark background and highlight surface features under the electron beam. Uranyl acetate not only scatters electrons for visibility but also acts as a mild fixative, preserving transient protein interactions on a millisecond timescale. This technique is particularly useful for initial characterization of purified proteins, offering nanometer-scale resolution in a straightforward workflow.^[100]^[101]^[102] Cryo-fixation via plunge freezing preserves biological samples in a frozen-hydrated state, preventing dehydration artifacts and maintaining native hydration. The sample, applied as a thin aqueous film on an EM grid, is rapidly plunged into liquid ethane cooled to approximately -180°C, achieving vitrification where water forms amorphous ice rather than crystalline structures. This method, pioneered by Dubochet and colleagues, revolutionized imaging of dynamic cellular processes by avoiding chemical fixatives and enabling observation close to physiological conditions. Vitrified specimens are transferred under liquid nitrogen to the TEM cold stage for imaging.^[103]^[104] Immunogold labeling allows precise localization of specific proteins within biological samples at the ultrastructural level, using antibodies conjugated to electron-dense gold nanoparticles. In pre-embedding protocols, fixed and permeabilized cells are incubated with primary antibodies targeting the protein of interest, followed by secondary antibodies linked to 5-20 nm gold particles for detection in TEM sections. This technique, originally developed in the 1970s, facilitates colocalization studies, such as identifying synaptic proteins in neuronal tissues, with gold particles appearing as dark dots against the background. Post-embedding variants apply labeling directly to ultrathin sections for better antigen access in resin-embedded material.^[105]^[106]^[107] Common artifacts in biological TEM preparation, particularly from ultramicrotomy, include compression—where sections appear shortened and distorted due to knife pressure—and knife marks, manifesting as parallel lines from edge imperfections. Compression can reduce effective resolution by up to 20-30% in the cutting direction, while knife marks obscure fine details. Mitigation strategies involve using low-angle diamond knives (25-35° wedge) to minimize compressive forces, reducing sectioning speed to 0.5-1 mm/s, and applying post-section stretching with chloroform vapor or a heated filament to restore dimensions without further damage. Proper block trimming and fresh knife maintenance also prevent tearing and uneven cuts.^[96]^[108]^[109]

Materials sample preparation

Sample preparation for transmission electron microscopy (TEM) of inorganic and crystalline materials focuses on producing electron-transparent regions, typically thinner than 100 nm, to enable high-resolution imaging of atomic structures, defects, and interfaces while minimizing beam damage and artifacts. These techniques are tailored to the mechanical properties of metals, ceramics, and minerals, ensuring uniform thinning and preservation of surface features relevant to materials science applications such as defect analysis and phase identification. Unlike softer biological samples, inorganic materials often require aggressive mechanical or chemical methods to achieve the necessary wedge-shaped or perforated geometries for optimal electron transmission. Electropolishing is a widely used electrochemical thinning method for metals and alloys, where a disc-shaped sample is immersed in an electrolyte and an electric field drives material removal from both sides until perforations form at the center, creating electron-transparent areas. For aluminum, a common electrolyte consists of 20% perchloric acid in ethanol, applied via twin-jet polishing at low temperatures around 5°C to control the etch rate and avoid overheating.^[110] Similar recipes, such as 10-20% perchloric acid in methanol at -40°C to -60°C, are employed for nickel-aluminum alloys and other metals like iron and copper, yielding smooth surfaces suitable for studying dislocations and grain boundaries.^[111]^[112] This technique provides high contrast by reducing thickness gradients, essential for revealing mass-thickness contrast in dense inorganic specimens. Dimpling followed by ion polishing is a mechanical-chemical hybrid approach that creates a wedge geometry for cross-sectional or plan-view analysis of layered materials like thin films and composites. Dimpling involves using a diamond paste or abrasive slurry to grind the sample center to approximately 20-50 μm thick, forming a shallow depression that minimizes the ion milling time needed for final thinning.^[113] Ion polishing then employs low-energy argon ions (e.g., 2-5 keV) from dual-beam sources at glancing angles (10-15°) to remove material progressively, achieving a tapered wedge with thicknesses varying from >1 μm at the edges to <100 nm at the tip.^[114] This method is particularly effective for brittle ceramics and semiconductors, as it reduces artifacts like preferential etching and ensures uniform electron transparency across the region of interest.^[115] Focused ion beam (FIB) milling enables site-specific preparation of inorganic samples, allowing precise extraction and thinning of targeted areas such as interfaces or defects in metals and minerals to thicknesses below 100 nm. In a dual-beam FIB-SEM system, a gallium ion beam (typically 30 kV) is used to mill trenches around a region of interest, followed by lift-out using a micromanipulator and in-situ thinning to electron transparency.^[116] Final low-voltage polishing (e.g., 5 kV) minimizes amorphization and curtaining effects, preserving crystalline structure for atomic-resolution imaging.^[117] This technique is invaluable for ultraprecious or heterogeneous materials, where bulk preparation might destroy key features.^[118] Shadow casting enhances topographic contrast in TEM by evaporating a thin layer (5-20 nm) of heavy metal, such as platinum-carbon or gold-palladium, onto the sample surface at an oblique angle (e.g., 45-60°), creating shadows that highlight surface relief and grain boundaries in inorganic specimens.^[119] The resulting replica, often supported on a carbon film, reveals elevations and depressions through differential metal deposition, with shadow lengths proportional to feature heights for quantitative topography measurement.^[120] This method is especially useful for non-conductive ceramics and fracture surfaces, providing three-dimensional-like visualization without extensive thinning. Cleaving offers a simple, artifact-free method for preparing thin sections of brittle minerals and crystals, exploiting natural cleavage planes to produce wedge-shaped fragments directly suitable for TEM. A sharp blade or mechanical cleaver is used to fracture the sample along preferred orientations, yielding areas as thin as 50-100 nm at the edges for immediate observation of lattice defects and phase boundaries.^[121] For petrographic studies, ion beam thinning may follow to refine the wedge, but cleaving alone suffices for many silicates and oxides, preserving original microstructure.^[122] This approach is favored for its speed and minimal sample alteration in geological materials.^[123]

Advanced fabrication techniques

Advanced fabrication techniques in transmission electron microscopy (TEM) encompass specialized methods designed to prepare nanoscale samples, particularly for challenging materials that require precise control over structure and minimal artifacts. These approaches enable the analysis of complex architectures, such as three-dimensional volumes or atomically thin layers, by integrating advanced tools like focused ion beam (FIB) systems with scanning electron microscopy (SEM) for serial sectioning. FIB-SEM hybrids facilitate 3D serial sectioning by combining ion milling for precise material removal with SEM imaging to capture successive cross-sections, allowing reconstruction of volumetric data with nanometer resolution. This technique is particularly valuable for soft or heterogeneous materials, where traditional sectioning may introduce distortions; automated milling and imaging cycles can process large volumes, such as 100 μm³ or more, in hours while minimizing beam damage through low-current operations.^[124] In practice, the system alternates between FIB excavation of thin slices (typically 5-20 nm thick) and SEM acquisition of secondary electron images, enabling correlative tomography that reveals internal morphologies without disassembling the sample.^[125] For two-dimensional (2D) materials like transition metal dichalcogenides or graphene, a user-friendly FIB in-situ lift-out technique prepares plan-view TEM samples by depositing a 100-200 nm Pt-C protective layer, attaching the lamella to a micromanipulator, transferring it to a TEM grid, and thinning to below 50 nm, achieving preserved lattice integrity.^[126] Such approaches are essential for studying layered interfaces, as they reduce substrate-induced artifacts compared to conventional exfoliation, and have been demonstrated to yield high-quality cross-sectional views of stacked 2D heterostructures.^[127] Chemical vapor deposition (CVD) enables in-situ growth directly on TEM grids, allowing real-time observation of nanostructure formation under controlled gas-phase conditions. In metal-organic CVD variants integrated with TEM holders, precursors are delivered to heated grids (e.g., at 500-800°C), promoting epitaxial growth of materials like III-V nanowires or 2D films while the microscope captures dynamic processes such as nucleation and coalescence.^[128] This technique minimizes transfer-induced contamination and supports studies of growth kinetics, with resolutions down to atomic scales during deposition.^[129] Replication casting preserves surface topographies for TEM by creating a negative mold of the original sample, which is then shadowed and backed for electron transparency. The process starts with casting a polymer or acetate film against the surface, followed by shadow evaporation of a heavy metal (e.g., platinum at 45° angle) and carbon coating to form a stable replica approximately 20-50 nm thick.^[130] This method is ideal for non-conductive or fragile surfaces, such as biological tissues or polymers, enabling indirect imaging of features like fractures or precipitates without direct sectioning. Extraction variants further allow isolation of embedded particles by dissolving the substrate, providing clean views of nanoscale inclusions.^[131] To minimize beam-induced damage during preparation, low-dose techniques such as argon (Ar) ion cleaning employ broad-beam ion polishing at reduced energies (e.g., 0.5-2 keV) to gently remove amorphous layers or implants from FIB-thinned samples. This post-milling step, often performed in a dedicated ion mill at 3 keV and 4° incidence, reduces the amorphous layer thickness to less than 12 nm (from 20-30 nm in untreated FIB samples), preserving crystalline order for high-resolution imaging.^[132] Standard thinning methods can be referenced as precursors, but advanced cleaning ensures artifact-free analysis of radiation-sensitive materials like semiconductors or organics.^[132] Recent advancements as of 2025 include automated electron microscopy sample preparation systems that enhance throughput and reproducibility by handling specialized workflows with minimal human intervention, and novel FIB techniques using redeposition to securely attach TEM lamellae to support grids, avoiding contamination issues during transfer.^[133]^[134]

Instrument variants and modifications

Scanning transmission electron microscopy

Scanning transmission electron microscopy (STEM) is a variant of transmission electron microscopy in which a finely focused electron probe is raster-scanned across the specimen using electromagnetic deflectors, forming images from signals collected at each position rather than parallel illumination.^[135] This scanning approach, pioneered by Albert Crewe in the 1970s, enables high-resolution mapping of atomic structure and composition, particularly suited for materials science and nanotechnology applications.^[135] Unlike conventional TEM imaging, which relies on phase contrast from a broad beam, STEM provides incoherent imaging modes that enhance interpretability for complex structures.^[135] The scanning process involves directing the electron beam pixel-by-pixel across the sample, with typical dwell times ranging from 10 to 100 μs per pixel to balance signal-to-noise ratio and acquisition speed.^[136] Electromagnetic deflectors control the beam position with sub-nanometer precision, allowing formation of two-dimensional images where each pixel corresponds to the collected signal at a specific probe location.^[137] A key imaging mode in STEM uses annular dark-field (ADF) detectors positioned below the sample to capture high-angle scattered electrons, producing Z-contrast images where signal intensity is proportional to approximately Z^{1.5-2} (with Z the atomic number), enabling direct visualization of atomic columns with sensitivity to elemental differences.^[138] STEM integrates seamlessly with electron energy-loss spectroscopy (EELS) for spectrum imaging, where EELS spectra are acquired at each scan position to generate spatially resolved maps of chemical composition and electronic structure at atomic scales.^[139] This combination allows simultaneous collection of structural and analytical data, with spectrum images revealing bond orientations or valence states through fine-structure analysis.^[139] Aberration correctors further enhance STEM performance, reducing probe aberrations to achieve sub-0.1 nm spatial resolution, as demonstrated in quantitative imaging of lattice defects and interfaces.^[140] One advantage of STEM's annular detectors is the capability for depth sectioning, where varying detector collection angles or probe defocus provides three-dimensional information by resolving features along the beam direction, particularly effective in aberration-corrected systems for thick specimens up to several nanometers.^[141] This optical sectioning reduces overlap from out-of-plane atoms, improving localization of dopants or nanostructures in depth.^[142]

Cryogenic and environmental TEM

Cryogenic transmission electron microscopy (cryo-TEM) enables the imaging of beam-sensitive specimens, such as biological macromolecules, by maintaining samples at low temperatures to preserve their native hydrated state and minimize radiation damage. Specimens are typically cooled using liquid nitrogen to temperatures around 80 K, while advanced liquid helium systems can achieve ultralow temperatures as low as 4 K to further suppress thermal motion and contamination buildup.^[143]^[144] Anti-contaminators, often cooled by liquid nitrogen, are employed to prevent the accumulation of residual gases or hydrocarbons on the sample, ensuring high-resolution imaging without artifacts.^[145] A key aspect of cryo-TEM involves embedding biomolecules in vitreous ice, a non-crystalline form of water that avoids the damaging ice crystal formation during freezing. This technique, pioneered by Jacques Dubochet and colleagues, involves rapid vitrification of aqueous samples to form thin films of amorphous ice, typically 10-100 nm thick, which suspends proteins or complexes in a near-native environment for structural analysis.^[103] The process preserves delicate structures like protein assemblies, allowing atomic-resolution imaging of dynamic conformations without dehydration or staining.^[146] As of 2025, emerging ultracold systems using liquid helium flow cryostats have demonstrated base temperatures as low as 4.37 K with exceptional stability (±0.004 K), enhancing applications in quantum material imaging.^[144] Environmental transmission electron microscopy (ETEM) extends TEM capabilities to non-vacuum conditions by introducing controlled gaseous or liquid environments around the specimen, facilitating the study of dynamic processes under realistic operating conditions. Differential pumping systems, using small apertures and ion or turbomolecular pumps, maintain high vacuum in the electron gun and detectors while allowing gas pressures up to 10 mbar in the sample chamber, enabling introduction of reactive gases such as hydrogen (H₂).^[147] This setup, advanced by Boyes and Gai in the 1990s, isolates the specimen region to prevent beam scattering by gas molecules outside the imaging area. In wet cell configurations for liquid environments, beam-induced effects like radiolysis, heating, and bubble formation pose significant challenges, but these can be mitigated through low-dose imaging protocols, reduced accelerating voltages, and the use of radical scavengers or flow systems to refresh the liquid and dissipate reaction products.^[148] Strategies such as minimizing electron flux below 1 e⁻/Å²/s and employing continuous liquid flow help distinguish intrinsic sample behavior from beam artifacts in electrochemical or biological studies.^[149] Cryo-TEM and ETEM have transformative applications in visualizing protein dynamics and catalytic processes. In cryo-TEM, time-resolved imaging captures conformational changes in biomolecules, such as enzyme-substrate interactions, revealing mechanisms at near-atomic resolution.^[150] For catalysis, ETEM observes nanoparticle restructuring under H₂ or O₂ atmospheres, providing insights into active site evolution during reactions like hydrogen oxidation on platinum surfaces.^[151] These techniques bridge static structural data with functional dynamics, advancing fields from structural biology to heterogeneous catalysis.^[152]

Aberration-corrected and low-voltage TEM

Aberration correction in transmission electron microscopy (TEM) primarily addresses spherical aberration, a dominant lens imperfection that limits resolution by causing rays at different distances from the optical axis to focus at varying points. Seminal developments include hexapole (sextupole) correctors, which compensate for third-order spherical aberration using a sequence of magnetic multipoles to introduce opposing aberrations, achieving a spherical aberration coefficient C_s reduced to below 1 μm in early implementations at 200 kV.^[153] Quadrupole-octupole correctors, employing quadrupoles for focusing and octupoles for aberration balancing, further refine this correction by simultaneously addressing spherical and chromatic aberrations while minimizing higher-order terms, enabling sub-angstrom resolutions.^[154] These multipole systems, integrated into the microscope column, expand the usable angular range for electron illumination, enhancing signal-to-noise ratios without sacrificing resolution.^[155] Low-voltage operation at 20–80 kV leverages the shorter de Broglie wavelength of electrons—approximately 0.005 nm at 80 kV—to maintain high resolution while boosting contrast for light elements like carbon and oxygen, which scatter weakly at higher voltages.^[156] This regime reduces knock-on damage in beam-sensitive materials, such as graphene or biological specimens, by lowering electron energy, yet preserves atomic-scale imaging when combined with aberration correction.^[157] For instance, at 60 kV, corrected systems achieve resolutions below 0.1 nm, facilitating direct visualization of atomic structures in low-Z materials.^[158] A key advantage of aberration-corrected TEM is the minimization of image delocalization, where uncorrected lenses blur features due to defocus variations across the field of view; correction reduces this effect to near-zero, allowing precise atomic positioning even in thick or tilted specimens.^[155] This improvement stems from the flatter phase contrast transfer function post-correction, which extends the resolution-limiting information limit rather than the traditional C_s-imposed cutoff.^[159] Commercial implementations include the JEOL JEM-ARM series, such as the ARM200F, equipped with a hexapole-based ASCOR corrector for C_s below 1 μm and operation down to 30 kV, delivering 0.078 nm STEM resolution at 200 kV.^[160] Similarly, the FEI (now Thermo Fisher) Titan platforms, like the Titan 80-300, incorporate quadrupole-octupole correctors for dual TEM/STEM modes, achieving sub-0.1 nm resolution at 80–200 kV with integrated monochromation to further suppress energy spread.^[161] However, low-voltage operation introduces trade-offs, notably increased chromatic aberration effects, as the coefficient C_c scales inversely with accelerating voltage, amplifying focus spread from source energy variations and leading to broader blur discs at 20–80 kV.^[162] While C_s correction mitigates spherical issues, chromatic limitations often necessitate additional monochromators or C_c correctors to sustain atomic resolution.^[163]

In-situ and dynamic TEM

In-situ transmission electron microscopy (TEM) enables the real-time observation of dynamic processes at the nanoscale, such as phase transformations, defect evolution, and chemical reactions, by integrating specialized holders and stages that apply controlled stimuli to samples while maintaining high-resolution imaging. These setups differ from standard TEM by incorporating environmental controls that mimic operational conditions, allowing researchers to correlate structural changes with applied mechanical, thermal, or electrochemical stresses. Dynamic TEM extends this capability through rapid imaging to capture transient events, providing insights into materials behavior under non-equilibrium conditions. Heating holders are essential for studying thermal processes in in-situ TEM, utilizing resistive heating elements to achieve temperatures up to 1500°C with minimal sample drift. These holders typically employ Joule heating via embedded filaments or microheaters, enabling precise temperature control for observing phenomena like sintering or melting in nanomaterials. For instance, furnace-type designs heat the entire grid, while MEMS-integrated variants focus heat on the observation area to reduce thermal gradients, supporting studies of catalyst activation at elevated temperatures.^[164]^[165]^[166] Mechanical biasing mechanisms facilitate quantitative tensile testing within the TEM column, often using push-pull configurations to apply uniaxial loads and measure stress-strain responses. In push-to-pull devices, an initial compressive force from a nanoindenter is converted to tensile strain via a lever system, achieving deformations up to several percent—typically around 10% in ductile materials—before failure. This approach has revealed dislocation dynamics and fracture mechanisms in metals and 2D materials, such as MXenes, where real-time imaging captures yield points and hardening.^[167]^[168]^[169] MEMS chips enhance in-situ TEM by integrating multiple stimuli on a single platform, such as combined heating and mechanical loading for bending tests on microbeams. These chips feature suspended structures like bending beams that allow precise deformation while embedding sensors for force and displacement feedback, enabling correlative studies of thermomechanical failure in semiconductors. For example, silicon microbeams under bending have been tested up to high temperatures, highlighting stress relaxation and plasticity without external holders.^[170]^[171] Liquid cells, employing silicon nitride (SiN) windows, permit in-situ observation of electrochemical reactions in aqueous environments by encapsulating liquids between thin, electron-transparent membranes. These windows, often 10-50 nm thick, confine electrolytes to paths of 100 nm to 1 µm, allowing imaging of processes like nanoparticle nucleation or dendrite growth during battery cycling. Integrated electrodes enable biasing for reactions such as lithium plating, revealing atomic-scale mechanisms of electrodeposition.^[172]^[173] High frame rates in dynamic TEM are achieved with direct electron detectors, which support imaging up to 1000 frames per second (fps) to resolve fast transients like crack propagation or reaction kinetics. These detectors, based on CMOS sensors, provide low-noise readout for electron counting, minimizing dose while capturing video-rate sequences essential for quantifying velocities in mechanical tests or diffusion events.^[174]^[175]

Limitations and future directions

Resolution and aberration limits

The theoretical resolution limit of transmission electron microscopy (TEM) is determined by the de Broglie wavelength of the electrons, given by λ = h / √(2 m e V), where h is Planck's constant, m is the electron mass, e is the electron charge, and V is the accelerating voltage. At 300 keV, this yields λ ≈ 0.002 nm, implying a diffraction limit of approximately λ/2 ≈ 0.001 nm.^[176] However, practical resolutions are significantly worse, typically around 0.05 nm at 300 keV, primarily due to spherical aberration introduced by electromagnetic lenses, characterized by the coefficient Cs, which causes defocusing of electrons depending on their trajectory angle.^[177] Inelastic scattering events further limit interpretability through delocalized interactions, where the scattering process extends over a finite distance rather than occurring at a point. For low-energy losses (ΔE << eV), the delocalization length scales approximately as 1/√(ΔE / V), reflecting the reduced localization at higher voltages due to increased electron velocity; this effect broadens features in energy-filtered images or spectra, often by several angstroms for plasmon losses around 10-20 eV. Achieving high resolution also demands stringent mechanical and temporal stability. Environmental vibrations must be suppressed below 1 nm root-mean-square to avoid blurring, while specimen drift rates should remain under 0.1 nm/s to enable atomic-scale imaging without distortion during exposure times of seconds.^[178] The information limit, set by factors like chromatic aberration and source coherence, often exceeds the Scherzer resolution—the aberration-limited point resolution at optimal defocus, d_S ≈ 0.66 Cs^{1/4} λ^{3/4}—in modern uncorrected TEMs, allowing potential for sub-angstrom detail if instabilities are controlled.^[179] In comparison to scanning electron microscopy (SEM), TEM achieves atomic-scale resolution (down to ~0.05 nm) by transmitting electrons through thin samples to reveal internal atomic arrangements, whereas SEM is limited to surface topology at ~0.5 nm or coarser due to its reliance on backscattered or secondary electrons from the sample exterior.^[180]

Sample and operational challenges

One major operational challenge in transmission electron microscopy (TEM) is beam-induced damage to samples, particularly in organic materials where radiolytic damage occurs at electron doses of 10-100 e/Å², leading to atomic ejection and structural disruption.^[181] This damage limits the usable electron dose, necessitating low-dose imaging techniques to preserve specimen integrity during high-resolution analysis.^[182] In inorganic samples, similar mechanisms apply but are often more pronounced at higher accelerating voltages, further complicating data acquisition for beam-sensitive materials. Contamination buildup from residual hydrocarbons in the vacuum system poses another significant issue, with deposition rates around 0.1 nm/min at room temperature, forming amorphous carbon layers that obscure fine details and alter contrast in images.^[183] This accumulation is exacerbated during prolonged exposures and requires periodic plasma cleaning or cryogenic cooling to mitigate, though it remains a persistent hurdle in achieving artifact-free results.^[184] Precise alignment is critical for reliable imaging, yet eucentricity errors exceeding 1 μm are common in standard setups without meticulous calibration, causing specimen drift and defocus during tilting or stage movements. Such misalignments can degrade resolution and necessitate frequent adjustments, increasing operational complexity. High instrument costs, often surpassing [$1](/page/1) million for advanced models, combined with the need for specialized training—typically involving multi-session programs costing hundreds to thousands of dollars—restrict accessibility to well-funded facilities and expert operators.^[185]^[186] Throughput remains low, with single-sample runs frequently extending several hours due to iterative alignment, focus optimization, and data collection under vacuum conditions around 10^{-7} torr to prevent scattering.^[187] This extended duration limits the number of samples processed per day, making TEM a low-volume technique despite its analytical power.^[188]

Emerging developments

Electron ptychography represents a promising advancement in TEM imaging, leveraging overlapping scan probes to reconstruct phase information and achieve resolutions below 0.5 Å without requiring aberration correction. This technique enables deep sub-angstrom resolution in uncorrected scanning transmission electron microscopes, down to 0.44 Å, by computationally recovering both amplitude and phase from diffraction patterns.^[189] Recent demonstrations have extended this capability to thicker samples and lower accelerating voltages, such as 20 keV, attaining 0.67 Å resolution in transmission mode, which broadens accessibility for atomic-scale phase recovery in diverse materials.^[190] Looking ahead, electron ptychography is poised to integrate with hybrid illumination schemes, potentially pushing resolutions toward 0.3 Å for real-time 3D structural analysis in complex systems.^[191] AI-driven automation is transforming TEM workflows by enabling real-time image reconstruction and anomaly detection, reducing manual intervention and accelerating data processing. Machine learning pipelines now automate crystal structure reconstruction from scanning transmission electron microscopy images, achieving end-to-end atomic model generation with minimal user input.^[192] These systems facilitate near-real-time aberration diagnosis and adaptive imaging, enhancing throughput in high-resolution experiments.^[193] Emerging AI frameworks further support generative models for predictive anomaly identification during acquisition, promising fully autonomous operation in post-2025 facilities for materials discovery.^[194] Such integrations could democratize advanced TEM, allowing non-experts to perform sub-angstrom analyses with automated feedback loops.^[195] Ultrafast TEM, utilizing femtosecond electron pulses, is advancing the study of transient phenomena like phonon dynamics at the nanoscale. Recent developments in laser-driven systems generate attosecond-scale pulses, enabling direct visualization of lattice vibrations and electron-phonon interactions with spatiotemporal resolution below 100 fs.^[196] These techniques have resolved defect-modulated phonon propagation in materials such as transition metal dichalcogenides, revealing energy dissipation pathways on picosecond timescales.^[197] Future iterations aim to combine femtosecond pulses with analytical capabilities, such as spectroscopy, to probe non-equilibrium states in energy materials, potentially informing next-generation photovoltaics and catalysts.^[198] Concepts for portable and miniaturized TEM instruments are gaining traction, focusing on compact designs that maintain high resolution without large vacuum systems. Innovations like photothermionic carbon nanotube cathodes enable low-cost, tabletop scanning electron microscopes operable at ambient pressures, achieving resolutions suitable for field-deployable nanoscale imaging (around 10 nm).^[199] These prototypes reduce footprint and energy demands, paving the way for integration into mobile labs for in-situ environmental monitoring. Post-2025, hybrid MEMS-based lenses could further shrink TEMs to handheld sizes, expanding applications in remote materials characterization and biology.^[200] Integration of TEM with synchrotron X-ray sources is fostering multimodal imaging platforms that combine atomic-scale electron contrast with element-specific X-ray mapping. Correlative approaches have demonstrated 3D tomography merging electron and X-ray ptychography for meteorite analysis, revealing nanoscale chemical distributions.^[201] Recent multimodal synchrotron datasets enable machine learning-driven fusion of TEM and X-ray data, enhancing resolution in bio-interaction studies of nanoparticles.^[202] Emerging setups, including high-temperature furnaces for in-operando experiments, promise synchronized electron-X-ray probing to track dynamic processes across scales, from atomic dynamics to macrostructures.^[203]

References

[1]
[PDF] Transmission Electron Microscope - SOEST Hawaii
Transmission electron microscopy (TEM) uses a beam of electrons transmitted through a thin specimen, forming an image. Modern TEM resolution is about 0.2 nm.
[2]
Conventional transmission electron microscopy - PMC - NIH
Feb 1, 2014 · The most frequently used TEM application in cell biology entails imaging stained thin sections of plastic-embedded cells by passage of an ...
[3]
[PDF] Transmission Electron Microscopy I. Introduction - FIU
In 1931, Knoll (inventor of SEM, 1935) and Ruska co- invent electron microscope and demonstrated electron images.
[4]
What Is an Electron Microscope (EM) and How Does It Work? - VA.gov
An electron microscope uses a beam of electrons to magnify images, unlike optical microscopes. It uses a focused beam of electrons to image the specimen.
[5]
[PDF] Ernst Ruska - Nobel Lecture
Therefore, Hans Busch [3] at Jena calculated the electron trajectories in ... by means of the short coil (“magnetic electron lens”) - i. e. the first recorded.Missing: original | Show results with:original
[6]
energy filter - Electron Microscopy - ETH Zürich
Nov 5, 2021 · 1938 First scanning transmission electron microscope (M. von Ardenne). 1939 First commercial TEM by Siemens (E. Ruska, B. von Borries). ~1940 ...Missing: commercialization | Show results with:commercialization
[7]
Ernst Ruska – Facts - NobelPrize.org
Ernst Ruska discovered that a magnetic coil could be used as a lens for electron beams and developed the first electron microscope in 1933.
[8]
Scientists - Siemens Global
By 1939, he and Borries had developed the first commercially viable electron microscope – the Siemens Super Microscope – for series production. The device ...<|separator|>
[9]
Electron Microscopy in Berlin 1928–1945 - ScienceDirect
The chapter describes various developments in the field of electron microscopy in Berlin from 1928–1945. In 1928, Ernst Ruska under the guidance of Max ...
[10]
The Nobel Prize in Physics 1986 - NobelPrize.org
The Nobel Prize in Physics 1986 was divided, one half awarded to Ernst Ruska for his fundamental work in electron optics, and for the design of the first ...
[11]
[PDF] Development of Holography Electron Microscope with Atomic ...
Hitachi developed its own first transmission electron microscope, the HU-1, in 1941. Hitachi supplied the first commercial model produced in Japan, the HU-.
[12]
In situ mechanical TEM: Seeing and measuring under stress with ...
Because the high voltage TEMs (⩾1 MeV) that were developed in the 1960s and 1970s offered a pole piece gap of about 10 mm or larger, several research ...
[13]
FE Electron Microscope IEEE Milestone Special Website
In 1969, Hitachi began developing field emission (FE) electron beam source technology. In just three years, Hitachi successfully developed an FE-SEM1 by ...
[14]
[PDF] Albert Crewe - Biographical Memoirs
Imaging single atoms. crewe made images of single atoms with the stem in 1970, and in 1975 obtained motion pictures of atoms moving along an amorphous carbon- ...<|control11|><|separator|>
[15]
Contributions to High Resolution and In Situ Electron Microscopy
Aug 1, 2018 · In summary, it can be said that Professor Hashimoto was a true pioneer of high resolution and in situ electron microscopy and that his tenacity, ...
[16]
Direct detectors and their applications in electron microscopy for ...
Jul 28, 2021 · From the 1980s onwards, charge coupled device (CCD) cameras were introduced to TEM and began to replace film as the most common device for ...
[17]
[PDF] Materials Analysis by Aberration-Corrected STEM
2000: Nion builds the first commercial EM aberration corrector in the world. ... The first results show that. 30 meV, 0.1 nm-level characterization of materials ...
[18]
Four-Dimensional Scanning Transmission Electron Microscopy (4D ...
In this paper, we review the use of these four-dimensional STEM experiments for virtual diffraction imaging, phase, orientation and strain mapping.
[19]
Developing and Evaluating Deep Neural Network-Based Denoising ...
A supervised deep CNN was developed to denoise ultra-low SNR TEM images of nanoparticles, outperforming existing methods by a PSNR of 12.0 dB.
[20]
Self-supervised machine learning framework for high-throughput ...
Apr 2, 2025 · In this paper, we introduce SHINE (Self-supervised High-throughput Image denoising Neural network for Electron microscopy), a self-supervised ...
[21]
Super-resolution electron ptychography of low dimensional ...
Jul 11, 2023 · We demonstrate that electron ptychographic phase reconstruction can recover spatial frequencies higher than those directly recorded in the experimental ...Missing: advancements | Show results with:advancements
[22]
Ultrafast Dynamics Revealed with Time-Resolved Scanning ...
Mar 17, 2023 · The development of the pump–probe technique with either laser or electron pulses has made it possible to induce dynamic transitions and follow ...
[23]
Elastic and Inelastic Scattering in Electron Diffraction and Imaging
`This is an excellent and comprehensive book describing the theory of the elastic and inelastic scattering of the electrons by crystals....This book fills a gap ...
[24]
Scattering Cross Sections in Electron Microscopy and Analysis
Aug 7, 2025 · The scattering cross section is the fundamental measure of the strength of a scattering interaction. All scattering in electron microscopy ...
[25]
The energy dependence of contrast and damage in electron ...
We have measured the dependence on electron energy of elastic and inelastic scattering cross-sections from carbon, over the energy range that includes 100 keV ...
[26]
Mechanisms of radiation damage in beam‐sensitive specimens, for ...
Jul 17, 2012 · For an incident energy of E0 = 100 keV, the Lenz model gives σi = 2.1 × 10−18 cm2 = 2.1 Mbarn, equivalent to an inelastic mean free path of ...
[27]
Monte Carlo electron-trajectory simulations in bright-field and dark ...
A Monte Carlo electron-trajectory calculation has been implemented to assess the optimal detector configuration for scanning transmission electron microscopy ( ...
[28]
electron lens - Electron Microscopy
Nov 5, 2021 · In a magnetic field, an electron experiences the Lorentz force F: F = -e (E + v x B) |F| = evBsin(v,B). E: strength of electric field. B ...
[29]
SEM Tech Explained, Part 2: A Guide to Electron Microscope Lenses
Nov 3, 2021 · The Lorentz force bends the path of electrons. diagram of an electromagnetic lens with electron beam Figure: Schematic Diagram of an ...
[30]
Magnetic Lens - an overview | ScienceDirect Topics
These curves may be of help in the design of magnetic lenses. The approximate focal length formula for strong magnetic lenses has been given (Huang, 1977):.
[31]
spherical aberration | Glossary | JEOL Ltd.
The amount of the spread (blur) is given by the product of the spherical aberration coefficient Cs and cube of the angle α, Csα3 (α is the angle between an ...
[32]
chromatic aberration | Glossary | JEOL Ltd.
Here, α is the convergence semi-angle of the electron beam with energy E, and Cc is the proportional factor of ΔE/E, called "chromatic aberration coefficient" ...
[33]
Aberrations | Corrected Electron Optical Systems - CEOS GmbH
Spherical aberration arises because the focus depends on the axial distance of the electron path. Physically this is a consequence of the fact, that lens fields ...
[34]
Transmission Electron Microscopy - Nanoscience Instruments
Transmission electron microscopy (TEM) is an analytical technique used to visualize the smallest structures in matter.
[35]
Objective lens in TEMs/STEMs - Electron microscopy
In TEM systems, the first condenser and final projector lenses have short focal length and their designs are similar to that of the objective lens. However, ...
[36]
Reciprocity relations in transmission electron microscopy: A rigorous ...
A concise derivation of the principle of reciprocity applied to realistic transmission electron microscopy setups is presented making use of the multislice ...Missing: theorem | Show results with:theorem
[37]
Reciprocity relations in transmission electron microscopy - PubMed
A concise derivation of the principle of reciprocity applied to realistic transmission electron microscopy setups is presented making use of the multislice ...Missing: theorem optics
[38]
Invited Review Article: Methods for imaging weak-phase objects in ...
A further description of the weak-phase object approximation is given in Chapter 3 of Ref. 3, and factors that can invalidate this approximation are discussed ...
[39]
The Theoretical Resolution Limit of the Electron Microscope
The contrast in the image of an atom is appreciably increased by defocusing and spherical aberration. Nevertheless, the contrast improves when the numerical ...Missing: original | Show results with:original
[40]
[PDF] Introduction to phase contrast & high-resolution TEM - nanoHUB
Scherzer defocus. Balance effect of spherical aberration with a specific value of negative defocus. Scherzer defocus: Scherzer resolution: ∆f = −. 4. 3. C s λ.
[41]
Contrast transfer function - abTEM - Read the Docs
The contrast transfer function (CTF) describes the aberrations of the objective lens in HRTEM and how the condenser system shapes the probe in STEM.
[42]
Image resolution - DoITPoMS
This can be defined as the resolution of a perfect electron lens, based on the Rayleigh criterion. Electron lenses are not perfect. They suffer from ...
[43]
A stable LaB6 nanoneedle field-emission point electron source - NIH
A LaB 6 nanoneedle that is fabricated using a focused ion beam shows a high reduced brightness, small energy spread, and especially high emission stability.
[44]
energy spread, energy width | Glossary | JEOL Ltd.
The thermionic-emission gun which uses a tungsten (W) filament has an energy spread of 1 to 3 eV at the cathode temperature of about 2800 K. The energy spread ...Missing: kT | Show results with:kT<|separator|>
[45]
A stable LaB 6 nanoneedle field-emission point electron source
Apr 6, 2021 · Due to the large fluctuations in thermionic emission, the energy spread is governed by the Maxwell–Boltzmann distribution and it is ...
[46]
[PDF] Introduction to Transmission Electron Microscopy
Dec 9, 2014 · Brightness (A/cm2/sr) at 200kV. ~5x105. ~5x106. ~5x108. ~5x108. ~5x108. Electron Source Size. 50μm. 10μm. 0.1-1μm. 10-100nm. 10-100nm. Energy ...
[47]
Schottky-emission electron gun, SE electron gun | Glossary | JEOL Ltd.
The brightness of the Schottky-emission electron gun is approximately 108 A/cm2sr, which is almost same as that of FEG. It is about three orders of ...Missing: LaB6 5 cm²
[48]
How Do You Make an Electron Beam?
May 11, 2019 · The emission area is substantially smaller for an FEG (nanometers) than a thermionic source (micrometers), resulting in superior brightness and, ...
[49]
Illumination: Condenser System - DoITPoMS
A typical TEM uses a system of two condenser lenses to control the beam incident on the sample. The first lens demagnetises the source.
[50]
Use of objective appertures - TEM - MyScope
There are a range of objective apperture sizes to choose from: the smaller the aperture, the greater the contrast and darker the image (because more electrons ...
[51]
Electron Microscope Aperture Overview - Ted Pella
Electron Microscope Aperture Overview ; Disc size, all, +0/-0.02mm ; Disc thickness, all, +0/-0.02mm ; Aperture holes, 5-10µm, ±1µm ; 11-70µm, ±2µm.
[52]
Analysis of electron intensity as a function of aperture size in energy ...
The dependence of electron intensity on condenser and objective aperture size in energy-filtered transmission electron microscope imaging was investigated ...
[53]
https://www.sciencedirect.com/science/article/pii/S0304399199001151
[54]
Real-time detection and single-pass minimization of TEM objective ...
Nov 10, 2016 · Minimization of the astigmatism of the objective lens is a critical daily instrument alignment task essential for high resolution TEM imaging.
[55]
Condenser lens stigmation - TEM - MyScope
Condenser lens stigmation, or astigmatism, occurs when the beam is not circular due to a non-uniform magnetic field, caused by non-perfect symmetry or ...
[56]
[PDF] Transmission Electron Microscopy - nanoHUB
Cs = 1 mm. Probe size. 0.3 nm. JEOL 2200FS with probe corrector. Probe size. 0.1 nm. Image corrector. Probe corrector. © 2015 University of Illinois Board of ...
[57]
Ludwig Reimer - Transmission Electron Microscopy
... by one number only. For Cs = 1 mm and. E = 100 keY (A = 3.7 pm), we find Il.z = 60 nm and Omin = 0.2 om. Narrow bands of higher spatial frequencies can be ...
[58]
Crossed laser phase plates for transmission electron microscopy
The main image is nearly unaffected, although the subtle “halo” artifact [15] seen around the protein (indicated by arrows in Figure 3) is suppressed by the ...
[59]
Chromatic Aberration - Practical Electron Microscopy and Database
Chromatic aberration in electron microscopy occurs when electrons of different velocities are diffracted differently, causing different wavelengths to focus ...<|control11|><|separator|>
[60]
What is Transmission Electron Microscopy? - Jeol USA
Vacuum System: Maintaining a high vacuum (typically below 10⁻⁵ Pa) prevents electron scattering, critical for clear image quality. JEOL systems use a ...How Tem Works · Comparative Analysis With... · Challenges In Sample...<|separator|>
[61]
Vacuum Systems/Levels in Electron Microscopes (EMs)
The highest vacuum level in the range of 10 -9 mbar to 10 -7 Pa is required in the gun area. Table 4463b lists the typical pressure ranges of EM parts.
[62]
Differential pumping aperture in EMs
In EM systems, the electron source and top end of the microscope is often pumped by an ion pump. This part of the microscope is almost entirely separated from ...
[63]
[PDF] TEM - Hitachi High-Tech
The eucentric specimen goniome- ter stage allows specimen tilting from +60° to -60° at 0.5°/step continuously and corresponding image recording. Fig. 2 shows a ...
[64]
Electron Microscopes - Vice President For Research
JEOL JEM-2000EXII Transmission Electron Microscope is equipped with a ±60° tilting (goniometer) stage, operates at accelerating voltages from 80kV to 200kV, ...
[65]
https://www.research.colostate.edu/min/electron-microscopes/
[66]
Electron Microscopy Facility Instrumentation - Brown University
The Cooling stage can also heat the sample up to about 60 °C. The temperature and the ramp-up profile are directly controlled through the xT User Interface.
[67]
Detective quantum efficiency of electron area detectors in electron ...
We present MTF and DQE measurements for four types of detector: Kodak SO-163 film, TVIPS 224 charge coupled device (CCD) detector, the Medipix2 hybrid pixel ...
[68]
Practical performance evaluation of a 10k × 10k CCD for electron ...
We have evaluated a 111-megapixel (10k × 10k) CCD camera with a 9 μm pixel size. ... Furthermore, CCD cameras have improved linearity and dynamic range (Brink ...
[69]
[PDF] XR401: High Sensitivity sCMOS Camera for TEM
XR401 Specifications. Sensor Size [pixels]. 2048x2048. Phosphor Pixel Size [µm]. 13 x 13. Active Pickup Region [mm]. 27 x 27. Digitization. 16 bits native, >16 ...
[70]
[PDF] Digital Imaging, an introduction - Research Resources Center
The CCD also has a large dynamic range of greater than. 10,000:1. The ... CCD based cameras have become practical for all TEM applications and provide ...Missing: specifications | Show results with:specifications
[71]
Evaluation of a hybrid pixel detector for electron microscopy
We describe the application of a silicon hybrid pixel detector, containing 64 by 64 pixels, each 170 μm 2 , in electron microscopy.Introduction · Hybrid Pixel Detectors · Medipix Mounting In The...Missing: binning gain<|separator|>
[72]
K2: A Super-Resolution Electron Counting Direct Detection Camera ...
Aug 6, 2025 · Low dose and low fluence electron microscopy experiments are the only practical way to acquire useful data from beam sensitive ...
[73]
Direct Detection Electron Energy-Loss Spectroscopy: A Method to ...
Aug 15, 2017 · For Sr mapping with the DD sensor, the data was recorded at 0.5 eV/channel, and then binned to 1 eV/channel prior to signal quantification.
[74]
Quantitative characterization of electron detectors for transmission ...
The DQE thus describes how the detector degrades the SNR, or how efficiently it detects an electron (the original name for DQE was 'useful quantum efficiency' ( ...
[75]
Thickness determination by measuring electron transmission in the ...
This paper aims at separating experimentally the dependence of contrast on mass thickness ρt from that on atomic number as indicated by Eq. (1)and at ...
[76]
A kinematical theory of diffraction contrast of electron transmission ...
This paper describes a kinematical theory of electron microscope images of dislocations observed by transmission in thin crystalline foils. The contrast is ...
[77]
Selected Area Diffraction - an overview | ScienceDirect Topics
In principle, the aperture allows only those electrons illuminating the area it defines to contribute to the diffraction pattern observed on the viewing screen.
[78]
Progress of Theoretical and Experimental Studies in Kikuchi Lines ...
Seishi KIKUCHI; Progress of Theoretical and Experimental Studies in Kikuchi Lines and Bands, Journal of Electron Microscopy, Volume 16, Issue 1, 1 January.
[79]
Direct observations of dislocations by transmission electron ...
Direct observations of dislocations by transmission electron microscopy: recollections of the period 1946-56. Peter Bernhard Hirsch.
[80]
Determination of the point resolution of high-resolution transmission ...
This paper introduces the information theory to overcome this circumstance and derives Scherzer conditions for evaluating instrument performance and the ...
[81]
Aberration-Corrected Z-Contrast Scanning Transmission Electron ...
Z-contrast STEM achieves several advantages over conventional TEM methods by using incoherently scattered electrons that are collected by a high-angle ...
[82]
Column-by-column compositional mapping by Z-contrast imaging
A phenomenological method is developed to determine the composition of materials, with atomic column resolution, by analysis of integrated intensities of ...
[83]
Optimal experimental design for exit wave reconstruction from focal ...
To get the best-possible performance from exit wave reconstruction from focal series in TEM, it is important to make the correct choices for the number of ...
[84]
[PDF] Exit Wavefunction Reconstruction - HREM Research Inc.
This technique simultaneously recovers the complex specimen exit plane wavefunction and fully compensates for all measurable lens aberrations. Using an ...
[85]
SINGLE: Atomic-resolution structure identification of nanocrystals by ...
Jan 29, 2021 · The pixel size was confirmed on the basis of the known lattice spacing of the graphene sheets containing the nanocrystals. TEM images of ...
[86]
Structure projection reconstruction from through-focus series of high ...
CTF fitting from Thon diffractograms can be applied to single HRTEM images [15], [25], [26], [30], but it requires large amorphous areas in the image which ...
[87]
From early to present and future achievements of EELS in the TEM
Jun 24, 2022 · This paper reviews the implementation of Electron Energy Loss Spectroscopy (EELS) in a Transmission Electron Microscope (TEM), as an essential tool for ...
[88]
EELS at very high energy losses - PMC - NIH
Electron energy loss spectroscopy has been investigated in the range from 2 keV to >10 keV with 200k V electrons using an optimized microscope–spectrometer ...
[89]
Spatial resolution in EFTEM elemental maps - KRIVANEK - 1995
Imaging filters developed over the last few years permit rapid elemental mapping by energy-filtering transmission electron microscopy (EFTEM), ...
[90]
Energy-filtered transmission electron microscopy: An overview
Aug 5, 2025 · This paper aims to give an overview of the technique of energy-filtered transmission electron microscopy (EFTEM).
[91]
Electron lambda-tomography - PNAS
Filtered back-projection and weighted back-projection have long been the methods of choice within the electron microscopy community for reconstructing the ...
[92]
Lorentz-electron vector tomography using two and three orthogonal ...
Feb 22, 2011 · Detailed comparisons are made between reconstructions using two and three tilt series, and between direct and filtered-back-projection methods.
[93]
Imaging Beam‐Sensitive Materials by Electron Microscopy
Feb 28, 2020 · where i) “SNR” refers to an SNR to measure signals with a target degree of uncertainty and a “Rose criterion” states an SNR of at least 5 to ...
[94]
Electron dose dependence of signal-to-noise ratio, atom contrast ...
In this paper we perform dose-dependent AC-HRTEM image calculations, and study the dependence of the signal-to-noise ratio, atom contrast and resolution on ...
[95]
Transmission Electron Microscopy of Biological Samples - IntechOpen
Latta and Hartmann used glass knife in ultramicrotomy ... These factors results in the formation of cutting artefacts such as chatter, compression, knife marks ...Missing: mitigation | Show results with:mitigation
[96]
[PDF] Guide to Sectioning on the Reichert-Jung Ultracut E Ultramicrotome
Both diamond and glass knives can be used to obtain ultra-thin sections for viewing with the TEM. However, due to the expense and added care one must use ...
[97]
[PDF] Sample preparation for Transmission electron microscopy (TEM)
Ultrathin sections are made at 50‐70 nm using a diamond knife and placed/collected on a grid of metal. Positive staining. Page 2. Side 2. Details in light ...
[98]
Serial-section electron microscopy using Automated Tape ... - NIH
In the ATUM (Automated Tape Collecting Ultramicrotome) method, sections are cut in a traditional way using an ultramicrotome and diamond knife with a water boat ...
[99]
Variations on Negative Stain Electron Microscopy Methods - NIH
Feb 6, 2018 · Uranyl acetate and formate also act as a fixative, preserving many protein-protein interactions on a millisecond time scale13, although the low ...
[100]
Brief Introduction to Contrasting for EM Sample Preparation
Oct 2, 2013 · Therefore, the double contrast method of ultrathin sections on grids with uranyl acetate and lead citrate is the standard routine ...
[101]
Negative and Positive Staining in Transmission Electron Microscopy ...
Negative staining of viral suspensions provides detailed information of virus particles' structure. It is a technique that can be quickly performed.
[102]
Cryo-electron microscopy of vitrified specimens - PubMed
Cryo-electron microscopy of vitrified specimens. Q Rev Biophys. 1988 May;21(2):129-228. doi: 10.1017/s0033583500004297. Authors. J Dubochet , M Adrian, J J ...Missing: seminal | Show results with:seminal
[103]
Automated vitrification of cryo-EM samples with controllable ... - Nature
May 27, 2022 · Vitrification via plunge-freezing using liquid ethane, or an ethane/propane mixture as a cryogenic, was shown to be a practical approach for ...Missing: seminal | Show results with:seminal
[104]
Pre-embedding immunogold labeling to optimize protein localization ...
Sep 11, 2014 · Pre-embedding immunogold labeling is a method for ultrastructural detection of proteins in leukocytes, using immunolabeling before embedding ...
[105]
Review of Post-embedding Immunogold Methods for the Study of ...
Oct 13, 2021 · Immunogold labeling for transmission electron microscopy (TEM) can be performed either before (pre-embedding immunogold; PrI) or after (post ...
[106]
Optimization of protocols for pre-embedding immunogold electron ...
Jun 3, 2021 · Immunogold labeling allows localization of proteins at the electron microscopy (EM) level of resolution, and quantification of signals.
[107]
Ultramicrotomy for Electron Microscopy - Bitesize Bio
Nov 1, 2024 · Ultramicrotomy is the process by which a sample is cut into very thin slices or “sections”, usually for imaging by transmission electron microscopy (TEM)Missing: marks | Show results with:marks
[108]
Ultramicrotomy Techniques for Materials Sectioning | Learn & Share
Oct 9, 2023 · Lowering the wedge angle of the knife from 45° to 35° or even 25° results in less compression and better structure preservation. However, this ...
[109]
[PDF] Electron Microscopic Observations of Interfacial Voids in Aluminum ...
Prior to the alkaline dissolution, all foils were electropolished in a 20% perchloric acid (70%) and ethanol (98%) bath at 5 °C for 5 min. Electropolishing was ...
[110]
[PDF] Chemically ordered dislocation defect phases as a new ...
Mar 9, 2025 · On rolled samples, TEM foils were prepared via electropolishing using a 10% perchloric acid and methanol mixture at −40 ◦C and with a 50 ...
[111]
https://rupert.wse.jhu.edu/wp-content/uploads/2025/04/Acta-Mat_Chemically-ordered-dislocation-defect-phases-as-a-new-strengthening-pathway-in-Ni-Al-alloys_2025.pdf
[112]
Optimized procedure for conventional TEM sample preparation ...
Conventional sample preparation consists of mechanical grinding and polishing, followed by ion-milling as the final thinning step. Mechanical thinning can be ...
[113]
A developed wedge fixtures assisted high precision TEM samples ...
Apr 11, 2017 · The traditional methods of the TEM sample preparation include dimpling,30 electro-polishing/chemical polishing,31 ultramicrotomy,32 cleaving ...
[114]
Advanced preparation of plan-view specimens on a MEMS chip for ...
Mar 7, 2022 · A novel method of TEM samples preparation in plan-view geometry was elaborated based on the combination of the wedge polishing technique and an enhanced ...
[115]
A review of focused ion beam milling techniques for TEM specimen ...
The primary advantage that is common to both methods is that the FIB tool allows for rapid production of site specific (to within ∼200 nm) TEM specimens. The ...
[116]
[PDF] Sample preparation for atomic-resolution STEM at low voltages by FIB
Jan 18, 2012 · All sample preparation has been carried out in modern Dual-Beam FIB microscopes capable of low-kV Gaş ion milling, but without additional ...
[117]
[PDF] Focused ion beam milling: A method of site-specific sample ...
Therefore, FIB sample preparation heralds a dramatic advance in the microstructural analysis of mineral surfaces and particu- larly of ultraprecious materials, ...
[118]
Vertical Pt–C Replication for TEM, A Revolution in Imaging Non ...
One of the earliest methods for preparing transmission electron microscopy (TEM) specimens used heavy metal shadow-casting by vacuum deposition (Mahl, 1942; ...
[119]
Metal Shadowing for Electron Microscopy - Radiology Key
Mar 4, 2017 · The shadow casting consists of evaporating a metal source at an oblique angle to the specimen. The smaller the objects being shadowed the ...Missing: inorganic | Show results with:inorganic<|separator|>
[120]
[PDF] TEM Samples Preparations - EPFL
Same sample after ion milling: 1h at. 5 keV, 10 min at 2 keV, 16° angle, 2 guns. Experimental conditions. After final polishing. The narrow shows the glue line.
[121]
[PDF] A Technique of Sample Preparation for Petrographic Investigation ...
Either a mineral is crushed and cleavage flakes mounted for observation, or else a small, thin core. (2-3 mm across) is further thinned by ion bombard- ment ...Missing: cleaving | Show results with:cleaving
[122]
Use of cleaved wedge geometry for plan-view transmission electron ...
Jul 15, 2021 · A fast, convenient, and easy to perform method for preparing plan-view transmission electron microscopy (TEM) specimens of brittle materials is proposed.Missing: mineral | Show results with:mineral
[123]
Enhanced FIB-SEM systems for large-volume 3D imaging - eLife
May 13, 2017 · Focused Ion Beam Scanning Electron Microscopy (FIB-SEM) can automatically generate 3D images with superior z-axis resolution, yielding data ...
[124]
Fast three-dimensional nanoscale metrology in dual-beam FIB–SEM ...
A different in-situ approach is dual-beam serial sectioning [18], [19], [20], where the FIB is used to serially cut slices from the sample while the SEM ...
[125]
A user-friendly FIB lift-out technique to prepare plan-view TEM ...
The methodology has been successfully applied to prepare samples from 2D materials such as, MoS2 thin film, vertically oriented graphene film (VG), as well as ...
[126]
A user-friendly FIB lift-out technique to prepare plan-view TEM ...
The user-friendly FIB lift-out technique is an easy, systematic, and implementable approach for preparing plan-view TEM samples of 2D materials, with four ...
[127]
In situ metal-organic chemical vapour deposition growth of III–V ...
The installation includes a gas handling system that delivers the precursors to III–V semiconductor growth under controlled conditions. The core microscope is a ...
[128]
Enabling In Situ Studies of Metal-Organic CVD in TEM
We report on the design and development of a metal-organic chemical vapor deposition (MOCVD) system integrated with an environmental transmission electron ...
[129]
Replica - Transmission Electron Microscopy - MyScope
The metal source is set at an average angle of 45° to the sample. A second coat, this time of carbon, is then evaporated perpendicular to the average surface ...
[130]
Revisiting the applications of the extraction replica sample ...
Extraction replication is a sample preparation technique for TEM that despite being over 60 years old, still provides a unique possibility to characterize ...
[131]
(PDF) Reducing focused ion beam damage to transmission electron ...
Aug 5, 2025 · We conclude that the use of low energy FIB and cleaning by argon BIB are particularly efficient techniques.
[132]
Scanning transmission electron microscopy: Albert Crewe's vision ...
Some four decades were needed to catch up with the vision that Albert Crewe and his group had for the scanning transmission electron microscope (STEM) in ...
[133]
[PDF] Transmission Electron Microscopy - AMC Workshop
Jun 3, 2019 · Major Imaging Contrast Mechanisms: 1. Mass-thickness contrast. 2. Diffraction contrast. 3. Phase contrast. 4. Z-contrast (S-TEM). Mass-thickness ...
[134]
Scanning Transmission Electron Microscopy
Scanning smaller areas corresponds to an increased magnification whereas increased pixel densities increase the apparent resolution. On the other hand, a fixed ...Missing: binning | Show results with:binning
[135]
Atomic number dependence of Z contrast in scanning transmission ...
Aug 17, 2018 · It has been reported that ADF signal is proportional to the nth power of the atomic number Z, i. e., the Z contrast in textbooks and papers.
[136]
Spectrum Imaging | EELS.info
In scanning transmission electron microscopy (STEM), the electron beam is focused into a small probe that scans over the sample to acquire spatial information ( ...
[137]
Sub-0.1 nm-resolution quantitative scanning transmission electron ...
May 11, 2012 · Experiments were performed on a Titan3 80–300 TEM/STEM equipped with aberration correctors for both the probe-forming and imaging lenses, a ...
[138]
Depth sectioning with the aberration-corrected scanning ... - NIH
Aberration correction therefore opens up the possibility of 3D imaging by optical sectioning. Here we develop a definition for the depth resolution for scanning ...
[139]
Depth sectioning of individual dopant atoms with aberration ...
Jan 9, 2008 · The ability to detect individual impurity atoms has been greatly enhanced by the development of aberration-corrected electron microscopes.
[140]
Ultra-Cold Cryogenic TEM with Liquid Helium and High Stability
Feb 1, 2024 · We introduce an ultra-cold liquid helium transmission electron microscope specimen holder, featuring continuous cryogen flow and vibration decoupling.Missing: 4K anti- contaminators
[141]
Do's and Don'ts of Cryo-electron Microscopy: A Primer on Sample ...
Jan 9, 2015 · Top off the TEM anti-contaminator with liquid nitrogen, which had been previously filled and cooled down for at least 20 min. Pre-tilt the ...<|separator|>
[142]
Effects of cryo-EM cooling on structural ensembles - Nature
Mar 31, 2022 · Subsequently, the grid is rapidly cooled, embedding the biomolecules in ice. Because the formation of ice crystals would damage the sample, the ...
[143]
Environmental transmission electron microscopy for catalyst ...
Atomic resolution has been obtained using environmental transmission electron microscopy (ETEM) by installing a spherical aberration corrector (Cs-corrector) ...
[144]
Strategies to overcome electron-beam issues in liquid phase TEM
Feb 9, 2024 · This article provides an overview of the electron-beam effects, and discusses various strategies in liquid cell TEM study of nucleation, growth, and self- ...
[145]
Experimental procedures to mitigate electron beam induced artifacts ...
The electron beam has a large effect on in situ experiments through indirect channels, with effects ranging from nanocrystal growth to bubble formation and ...
[146]
Cryo-EM in molecular and cellular biology - ScienceDirect.com
Jan 20, 2022 · This review summarizes the current state of methods and results achievable by cryo-electron microscopy (cryo-EM) imaging for molecular, cell, and structural ...Missing: seminal | Show results with:seminal
[147]
Recent advances in in-situ transmission electron microscopy ... - NIH
In this article, we present a comprehensive overview of the application of in situ TEM techniques in heterogeneous catalysis.
[148]
Cryo-EM in molecular and cellular biology
Jan 20, 2022 · This review summarizes the current state of methods and results achievable by cryo-electron microscopy. (cryo-EM) imaging for molecular, cell ...
[149]
A spherical-aberration-corrected 200 kV transmission electron ...
A hexapole corrector system was constructed for compensation of the spherical aberration of the objective lens of a transmission electron microscope.
[150]
Optimized Quadrupole-Octupole C 3 /C 5 Aberration Corrector for ...
Aug 1, 2008 · It is shown how the Nion fifth-order aberration corrector can be used to adjust and reduce some of the fourth- and fifth- order aberrations ...Missing: seminal | Show results with:seminal<|separator|>
[151]
Aberration correction for TEM - ScienceDirect.com
A further important benefit of aberration correction in the TEM is the reduced delocalization ... In other words, the single image from the aberration-corrected ...
[152]
Dynamics of the charging-induced imaging instability in ... - NIH
where λ = 0.00418 is the de Broglie wavelength of electrons under 80 kV accelerating voltage, δ = 1 is the defocus spread due to aberration, μ is the ...
[153]
(PDF) Sub-Angstrom Low-Voltage Performance of a ... - ResearchGate
Lowering the electron energy in the transmission electron microscope allows for a significant improvement in contrast of light elements and reduces knock-on ...
[154]
Resolution Improvement in Aberration-Corrected Low- Voltage TEM ...
Mar 1, 2016 · We have developed a low-voltage electron microscope equipped with a monochromator and Delta-type Cs correctors, which shows atomic resolution at ...
[155]
New views of materials through aberration-corrected scanning ...
Successful aberration correction came first with the scanning electron microscope [3] followed by the transmission electron microscope (TEM) [4–6] and the STEM ...
[156]
JEM-ARM200F NEOARM Atomic Resolution Analytical Electron ...
JEM-ARM200F comes with JEOL's unique cold field emission gun (Cold FEG) and a new Cs corrector (ASCOR) that compensates for higher order aberrations.Missing: FEI Titan
[157]
FEI Titan 80-200 Aberration Corrected (S)TEM/EDS/EELS
The Titan microscope is a image-aberration-corrected scanning transmission electron microscope (STEM/TEM) capable of producing images with .08nm resolution.Missing: commercial JEOL ARM
[158]
Aberration correction for low voltage optimized transmission electron ...
Uncorrected conventional electron microscopy limited mainly by chromatic and spherical aberration is not able to achieve spatial resolution better than 50 λ [1] ...
[159]
Chromatic Aberration Correction for Atomic Resolution TEM Imaging ...
Aug 9, 2016 · The chromatic aberration translates the energy spread of the electron source and instabilities of the accelerating voltage into a focus spread.
[160]
[PDF] 1 Experimental set up for in situ Transmission Electron Microscopy ...
The maximum achievable temperature primarily depends upon the modified heating holder and varies between 1000 °C and 1500 °C, depending upon the source and ...Missing: elements seminal
[161]
Development of a microfurnace dedicated to in situ scanning ...
May 16, 2024 · The heating element is heated by the Joule effect. Its maximal admissible temperature is around 1400 °C given the heating element's small ...Missing: seminal | Show results with:seminal
[162]
[PDF] Situ heating transmission electron microscope holder for atomic ...
These utilized localised resistive heat- ing elements to provide heat to the sample support. As a result of these commercially available heating holders,.
[163]
Advances on in situ TEM mechanical testing techniques - Frontiers
In this review, we summarize recent advances on in situ TEM mechanical characterization techniques, including classical tension holders, nanoindentation holders ...
[164]
In Situ Quantitative Tensile Testing of Antigorite in a Transmission ...
Feb 20, 2020 · A push-to-pull deformation device is used to perform quantitative tensile ... strain (several percent) was accumulated before failure.
[165]
Elastic properties and tensile strength of 2D Ti3C2Tx MXene ...
Feb 21, 2024 · The PTP microdevice converts the pushing force into plane tensile force on Ti3C2Tx through the “push-to-pull” mechanism with a loading rate 10 ...
[166]
A novel MEMS stage for in-situ thermomechanical testing of single ...
We present a novel silicon MEMS stage for in-situ bending test of micro/nanoscale samples at high temperature. The stage minimizes uniaxial state of stress ...
[167]
MEMS Device for Quantitative In Situ Mechanical Testing in Electron ...
In this work, we designed a micro-electromechanical systems (MEMS) device that allows simultaneous direct measurement of mechanical properties during ...Mems Device For Quantitative... · 2.2. Sensor Design · 4.1. Sensors Performance<|separator|>
[168]
Liquid cell transmission electron microscopy and its applications - NIH
This paper reviews in situ TEM experiments of liquid samples, with a focus on microchip encapsulated liquid cell TEM.
[169]
https://www.nature.com/articles/s41467-024-45657-6
[170]
Rapid low dose electron tomography using a direct electron ... - NIH
Oct 5, 2015 · We demonstrate the ability to record a tomographic tilt series containing 3487 images in only 3.5 s by using a direct electron detector in a ...
[171]
Direct Electron Detectors - ScienceDirect.com
They can read out images continuously with a frame rate that can range from 1 to 1000 Hz or more. The original designs for digital consumer cameras (Sunetra ...
[172]
Introduction to Electron Microscopy
Thus, the wavelength of electrons is calculated to be 3.88 pm when the microscope is operated at 100 keV, 2.74 pm at 200 keV, and 2.24 pm at 300 keV.
[173]
Research - Outline
Spherical aberration corrected High-Resolution Transmission Electron Microscopes (HRTEM) provide point resolution of 0.05 nm with 300 keV electrons [1] but ...
[174]
Automatic drift compensation for nanoscale imaging using feature ...
Mar 20, 2023 · An implementation of drift compensation for imaging at the nanoscale is presented. The method is based on computer vision techniques and hence applicable to ...<|separator|>
[175]
Point Resolution in EMs - Electron microscopy
For modern median voltage TEMs, the Scherzer point resolution is lower than the information limit, which is controlled by the temporal coherence of the electron ...
[176]
TEM vs. SEM Imaging: What's the Difference? - JEOL USA blog
TEM imaging can achieve excellent spatial resolutions, with resolutions of less than 50pm being reported whereas SEM imaging is limited to ~0.5 nm. SEM Imaging ...
[177]
Quantitative Analysis of Electron Beam Damage in Organic Thin Films
Beam effects can vary depending on parameters such as electron dose rate, temperature during imaging, and the presence of water and oxygen in the sample.Missing: Å² | Show results with:Å²
[178]
Understanding Radiation Damage in Cryo-Electron Microscopy
That is, at voltages above 400 kV straight displacement by the electron will result in so-called knock-on damage. Cryo-EM and the Electron Dose. Cryo-EM is ...
[179]
Contamination mitigation strategies for scanning transmission ...
Hydrocarbon contamination has been a limiting factor in electron microscopy since the technique was invented. Vacuum systems using oil-based rotary and ...
[180]
[PDF] Contamination of TEM Holders Quantified and Mitigated - arXiv
Hydrocarbon contamination plagues high-resolution and analytical electron microscopy by depositing carbonaceous layers onto surfaces during electron ...
[181]
The must-have multimillion-dollar microscopy machine | News - Nature
Aug 31, 2021 · The Can$10 million (US$8 million) costs for purchase and subsequent upgrade of McGill's Titan Krios were partially covered by grants from the ...
[182]
Electron Microscopy Training - Yale School of Medicine
The training fee of $1,000.00 will be charged after the training sessions are completed. This fee includes training sessions and 6 hours of prepaid practice ...Missing: 1M | Show results with:1M
[183]
TEM sample preparation techniques | University of Gothenburg
Dec 8, 2023 · While the whole process can take up to several days when performed manually, it can be shortend to a couple of hours in the automated microwave- ...
[184]
How long does electron microscopy take? - Quora
Dec 4, 2020 · Preparation of a specimen for EM is time consuming and not easy. It might take a day or at least several hours to prepare a specimen for viewing ...
[185]
Achieving sub-0.5-angstrom–resolution ptychography in ... - Science
Feb 22, 2024 · We demonstrate electron ptychography in an uncorrected scanning transmission electron microscope (STEM) with deep subangstrom spatial resolution down to 0.44 ...
[186]
Sub-ångström resolution ptychography in a scanning electron ...
Oct 14, 2025 · A relatively new approach to improving the resolution in TEM, which does not require an aberration corrector or a high-pixel count electron ...Missing: advancements | Show results with:advancements
[187]
Imaging thick objects with deep-sub-angstrom resolution and ... - arXiv
Feb 25, 2025 · Although deep-sub-angstrom resolution has been achieved with multislice electron ptychography, the sample thickness is typically very limited.
[188]
AutoMat: Enabling Automated Crystal Structure Reconstruction from ...
May 19, 2025 · An end-to-end, agent-assisted pipeline that automatically transforms scanning transmission electron microscopy (STEM) images into atomic crystal structures.
[189]
Automating Electron Microscopy through Machine Learning and ...
Aug 6, 2025 · Near-real-time diagnosis of electron optical phase aberrations in scanning transmission electron microscopy using an artificial neural network.
[190]
Artificial Intelligence‐Assisted Workflow for Transmission Electron ...
Oct 22, 2025 · AI-Assisted Workflow for (Scanning) Transmission Electron Microscopy: From Data Analysis Automation to Materials Knowledge Unveiling.
[191]
A New Age of Electron Microscopy: Magnifying Possibilities with ...
Apr 7, 2025 · Automation creates a new age of electron microscopy for materials science, enabling faster data collection, reduced bias, and more complex ...Missing: 2024 | Show results with:2024
[192]
Development of a femtosecond analytical electron microscopy ...
Mar 3, 2025 · Ultrafast transmission electron microscopy (UTEM) has gained wide applications in the nanoscale dynamics with femtosecond, even attosecond, ...
[193]
[PDF] Laser-driven ultrafast transmission electron microscopy - OSTI.GOV
Oct 16, 2025 · Disadvantages. Increased space charge effects are observed due to the low electric fields on the photocathode compared to FEG.
[194]
Ultrafast momentum-resolved visualization of the interplay between ...
Apr 2, 2025 · However, the limited energy resolution of our ultrafast electron microscope does not allow us to directly resolve phonon losses, which are ...
[195]
Concept and demonstration of a low-cost compact electron ... - Nature
Aug 28, 2025 · The scanning electron microscope (SEM) delivers high resolution, high depth of field, and an image quality as if microscopic objects are ...
[196]
Concept and demonstration of a low-cost compact electron ...
Aug 28, 2025 · Concept and demonstration of a low-cost compact electron microscope enabled by a photothermionic carbon nanotube cathode. Nat Commun. 2025 Aug ...Missing: portable miniaturized 2024
[197]
Multimodal x-ray and electron microscopy of the Allende meteorite
Sep 20, 2019 · We combine x-ray ptychography and scanning transmission x-ray spectromicroscopy with three-dimensional energy-dispersive spectroscopy and electron tomography
[198]
Three-dimensional, multimodal synchrotron data for machine ...
Feb 24, 2025 · We present a unique, multimodal synchrotron dataset of a bespoke zinc-doped Zeolite 13X sample that can be used to develop advanced deep learning and data ...
[199]
A high-temperature furnace for multi-modal synchrotron-based X-ray ...
Jul 1, 2025 · This furnace offers a robust and flexible platform for high-temperature synchrotron studies across materials science, including metals, ceramics, and energy ...