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Localized surface plasmon

A localized surface plasmon (LSP) arises from the confinement of surface plasmons within a metal nanoparticle whose dimensions are comparable to or smaller than the wavelength of incident light, resulting in non-propagating collective oscillations of conduction electrons on the nanoparticle surface.^[1] This phenomenon, often referred to in the context of its resonant excitation as localized surface plasmon resonance (LSPR), occurs when electromagnetic waves interact with conductive nanoparticles, typically composed of noble metals such as gold, silver, or copper, leading to coherent electron oscillations at a specific resonant frequency.^[2] The resonant wavelength is highly sensitive to the nanoparticle's size, shape, composition, interparticle spacing, and surrounding dielectric environment, enabling tunable optical responses in the visible and near-infrared spectra.^[2] Key properties of LSPs include intense local electromagnetic field enhancement near the nanoparticle surface, with enhancement factors that can exceed 100-fold and decay lengths typically ranging from 5 to 30 nm, making them ideal for probing molecular-scale interactions without interference from bulk refractive index changes.^[1] The extinction spectrum of LSPs features sharp peaks due to absorption and scattering, described by models such as the Mie theory for spherical particles, where the peak position shifts proportionally with environmental refractive index changes (e.g., sensitivities up to 200 nm/RIU).^[2] Unlike propagating surface plasmons on extended metal films, LSPs are inherently localized, avoiding propagation losses and allowing for compact, nanoscale optical devices.^[1] These attributes arise from the resonant collective oscillations of electrons, which impart high molar extinction coefficients on the order of 10¹¹ M⁻¹ cm⁻¹, far surpassing those of organic dyes.^[2] LSPs have found widespread applications in biosensing, where refractive index shifts upon biomolecular binding enable label-free detection of analytes such as proteins, DNA, and pathogens with limits of detection down to the attomolar range (e.g., 15 attomoles for cardiac troponin T).^[3] In spectroscopy, they enhance techniques like surface-enhanced Raman scattering (SERS) and metal-enhanced fluorescence (MEF), amplifying signals for single-molecule analysis.^[2] Emerging uses include photocatalysis for renewable energy applications, such as improving dye-sensitized solar cell efficiencies to over 7%, and environmental monitoring for volatile organic compounds at parts-per-million levels.^[3] Ongoing developments focus on integrating LSPs with microfluidics and fiber optics for portable, real-time diagnostic tools.^[1]

Fundamentals

Definition and Physical Origin

A localized surface plasmon (LSP) refers to the coherent, collective oscillations of conduction electrons confined to the surface of metallic nanoparticles or nanostructures, typically with dimensions less than 100 nm, which are comparable to or smaller than the wavelength of the incident light. This confinement arises due to the finite size of the structure, preventing the plasmon from propagating and instead localizing the electromagnetic field, often resulting in significant enhancement of the local electric field near the particle surface by factors of 10 to 100 or more at resonance.^[1]^[4] The physical origin of LSPs stems from the interaction between an incident electromagnetic wave and the free electrons in the metal, which become polarized and driven into oscillatory motion. When the frequency of the incident light matches the natural frequency of these electron oscillations—determined by the restoring force from the positive ion background and Coulomb interactions—a resonance condition is met, leading to strong absorption, scattering, and field localization without the need for wave propagation. This phenomenon is distinct from extended plasmon modes, as the subwavelength confinement in discrete nanostructures quantizes the electron motion, enhancing sensitivity to the local environment.^[1]^[4] The concept of LSPs was first theoretically described in 1908 through Gustav Mie's solution to Maxwell's equations for light scattering by spherical particles, explaining the vivid colors of metal colloids observed as early as Michael Faraday's experiments in the 1850s. Although foundational, practical observation and control of LSPs advanced significantly in the 1990s with the rise of nanotechnology, enabling the synthesis of well-defined nanoparticles and their integration into applications like sensing. Qualitatively, the resonance frequency of an LSP depends on the nanoparticle's size, shape, and surrounding dielectric medium; for instance, increasing particle size typically causes a red-shift in the resonance wavelength due to radiative damping and induced multipolar effects, while elongated shapes like nanorods introduce additional tunable modes, and higher refractive index environments further red-shift the peak.^[4]^[5] Prototypical examples of LSPs occur in gold and silver nanoparticles, where the resonance falls in the visible spectrum owing to the interplay between free-electron Drude-like behavior and interband transitions. For spherical gold nanoparticles (around 20-50 nm diameter) in water, the LSP resonance peaks near 520 nm, producing a ruby-red color and enabling applications in bioimaging due to biocompatibility. Silver nanoparticles, with resonances around 400-450 nm, exhibit sharper peaks and higher field enhancements because of lower damping from interband absorption, making them ideal for surface-enhanced spectroscopy.^[1]^[6]

Theoretical Framework

The theoretical framework for localized surface plasmons (LSPs) is grounded in classical electrodynamics, describing the collective oscillations of conduction electrons in metal nanostructures confined by their geometry. For nanoparticles much smaller than the wavelength of light (typically r \ll \lambda / 10), the quasi-static approximation applies, neglecting retardation effects and treating the incident field as uniform across the particle. In this regime, the induced dipole moment \mathbf{p} = \alpha \mathbf{E}_0 is characterized by the polarizability \alpha, which for a spherical metal nanoparticle of radius r embedded in a dielectric medium with permittivity \epsilon_d is given by

\alpha = 4\pi r^3 \frac{\epsilon_m(\omega) - \epsilon_d}{\epsilon_m(\omega) + 2\epsilon_d},

where \epsilon_m(\omega) is the frequency-dependent permittivity of the metal. This expression derives from solving Laplace's equation for the electrostatic potential around the sphere, matching boundary conditions at the interface. The LSP resonance occurs when the real part of the denominator approaches zero, yielding the Fröhlich condition \mathrm{Re}[\epsilon_m(\omega)] = -2\epsilon_d, at which the polarizability diverges and the scattering and absorption are maximized.^[7] This condition highlights the strong dependence on the metal's dielectric function, typically modeled classically by the Drude-Lorentz dispersion relation

\epsilon_m(\omega) = \epsilon_\infty - \frac{\omega_p^2}{\omega^2 + i\gamma\omega},

where \epsilon_\infty is the high-frequency permittivity, \omega_p the plasma frequency, and \gamma the damping rate due to electron collisions. For particles of arbitrary size, the full electrodynamic treatment is provided by Mie theory, which solves Maxwell's equations exactly for spherical scatterers using vector spherical harmonics. The total extinction cross-section is \sigma_\mathrm{ext} = \sigma_\mathrm{sca} + \sigma_\mathrm{abs}, with the scattering cross-section

\sigma_\mathrm{sca} = \frac{2\pi}{k^2} \sum_{l=1}^\infty (2l + 1) \left( |a_l|^2 + |b_l|^2 \right)

and the absorption cross-section

\sigma_\mathrm{abs} = \frac{2\pi}{k^2} \sum_{l=1}^\infty (2l + 1) \mathrm{Re}(a_l + b_l),

where k = \omega \sqrt{\epsilon_d}/c is the wavenumber in the medium, and a_l, b_l are the Mie coefficients depending on the size parameter x = k r and the relative refractive index m = \sqrt{\epsilon_m / \epsilon_d}.^[8] In the small-particle limit (x \ll 1), the dominant l=1 dipole terms reduce to the quasi-static polarizability, with higher-order multipoles negligible. However, for larger particles (r > 20 nm), retardation effects introduce phase variations across the particle, shifting the dipole resonance to higher energies (blueshift) and exciting multipolar modes (quadrupole for l=2, etc.), which broaden the spectrum and reduce the dipole dominance. The surrounding medium influences all resonances through \epsilon_d, scaling the effective wavelength and modulating the Fröhlich condition. Non-spherical geometries introduce shape-dependent resonances via depolarization effects. For ellipsoidal particles in the quasi-static limit, Gans theory extends the spherical case by incorporating principal depolarization factors L_i (with \sum_i L_i = 1), yielding axis-specific polarizabilities

\alpha_i = 4\pi V \frac{\epsilon_m - \epsilon_d}{L_i (\epsilon_m - \epsilon_d) + \epsilon_d},

where V is the particle volume.^[9] Resonances occur at \mathrm{Re}[\epsilon_m] = \epsilon_d \frac{1 - L_i}{L_i}, splitting the single spherical mode into degenerate transverse modes (higher L_i \approx 1/3) and a red-shifted longitudinal mode (low L_i) for prolate shapes like nanorods, where the aspect ratio tunes the splitting. For example, in gold nanorods, the longitudinal mode can extend into the near-infrared as the aspect ratio increases beyond 2. This shape tunability arises from the anisotropic electron oscillation along different axes, with the surrounding medium further shifting modes via \epsilon_d. In ultrasmall particles (r < 5 nm), classical models break down due to quantum confinement and non-local dielectric responses, where electron wavevector dependence (spatial dispersion) smears the sharp Drude-Lorentz resonances, but the framework remains rooted in the local Drude description for larger scales.

Relation to Other Plasmonic Phenomena

Propagating Surface Plasmons

Propagating surface plasmons, also known as surface plasmon polaritons (SPPs), are electromagnetic waves that propagate along the interface between a metal and a dielectric medium, arising from the coupling of light with collective oscillations of conduction electrons at the boundary. These modes are characterized by fields that decay exponentially perpendicular to the interface, typically on the order of hundreds of nanometers into the dielectric and much shorter distances into the metal due to the skin depth. The physical origin traces back to the coherent longitudinal charge density oscillations at the surface, first theoretically described in the context of plasma losses in thin metal films.^[10] The dispersion relation for SPPs describes the relationship between the frequency \omega and the wavevector k parallel to the interface, given by

k = \frac{\omega}{c} \sqrt{\frac{\varepsilon_m(\omega) \varepsilon_d}{\varepsilon_m(\omega) + \varepsilon_d}},

where c is the speed of light in vacuum, \varepsilon_m(\omega) is the frequency-dependent dielectric function of the metal, and \varepsilon_d is the dielectric constant of the adjacent medium. This relation shows that for small k, the dispersion approaches the light line in the dielectric (\omega = c k / \sqrt{\varepsilon_d}), while at large k, it asymptotically approaches the surface plasmon frequency \omega_{sp} = \omega_p / \sqrt{1 + \varepsilon_d}, where \omega_p is the bulk plasma frequency of the metal. The requirement \operatorname{Re}(\varepsilon_m + \varepsilon_d) < 0 ensures the existence of bound modes. Excitation of SPPs necessitates overcoming the momentum mismatch between incident photons and the SPP wavevector, since k > \omega / c. Common methods include prism coupling via the Otto and Kretschmann configurations, where a high-refractive-index prism provides the necessary parallel momentum component through evanescent waves generated by total internal reflection. In the Otto configuration, the prism is separated from the metal film by a thin dielectric gap, allowing the evanescent field to couple to surface plasmons on the outer metal-dielectric interface. The Kretschmann configuration places a thin metal film directly on the prism, enabling excitation at the film-dielectric boundary opposite the prism. Grating coupling uses periodic surface structures to provide the reciprocal lattice vector for momentum compensation, allowing direct illumination without prisms.^[11]^[12] SPP propagation is limited by ohmic losses in the metal, arising from interband transitions and electron scattering, leading to an imaginary component in the wavevector \operatorname{Im}(k). The propagation length L, defined as the distance over which the intensity decays to $1/e of its initial value, is approximately L \approx 1 / (2 \operatorname{Im}(k)) and typically ranges from tens of microns at visible wavelengths to hundreds of microns in the near-infrared for silver-air interfaces. For example, measurements on gold stripes yield propagation lengths around 39 \mum.^[13] In contrast to localized surface plasmons, which are non-propagating resonances confined to subwavelength metal nanoparticles and exhibit strong spatial localization with coherence lengths below the diffraction limit, SPPs maintain extended spatial coherence over propagation distances much larger than the wavelength, enabling waveguide-like behavior. While localized modes are primarily tuned by nanoparticle shape and size, SPP properties are modulated by the interface geometry, such as thickness in thin films or periodicity in gratings, allowing control over dispersion and confinement without discrete particle effects.^[14]

Bulk and Volume Plasmons

Bulk plasmons, also known as volume plasmons, refer to the collective oscillations of free electrons throughout the volume of a metal or semiconductor, extending uniformly without confinement to surfaces or interfaces. These excitations arise from the coherent motion of the electron gas in response to perturbations, distinct from localized modes by their lack of spatial restriction and involvement of the entire bulk material.^[15] The characteristic frequency of bulk plasmons, known as the bulk plasmon frequency \omega_p, is given by the formula

\omega_p = \sqrt{\frac{n e^2}{\epsilon_0 m}},

where n is the free electron density, e the elementary charge, \epsilon_0 the vacuum permittivity, and m the electron effective mass.^[15] In the simplest hydrodynamic or Drude-like model, this frequency is dispersionless, meaning it remains constant independent of the wavevector k. However, in real materials, band structure effects introduce weak dispersion, particularly at higher k values. When bulk plasmons couple with photons, they form volume plasmon polaritons, quasiparticles exhibiting slight dispersion due to the light-matter interaction, typically observable above the plasmon frequency. Unlike propagating surface plasmons, which are confined to interfaces, volume modes require high momentum transfer for excitation and are commonly probed using electron energy loss spectroscopy (EELS).^[16] In finite-sized structures such as nanoparticles, bulk volume plasmons hybridize with surface-localized modes, leading to a spectrum of resonances where the distinction blurs depending on particle size.^[17] For instance, in semiconductor quantum dots, size quantization effects shift the plasmon frequencies, with smaller dots exhibiting higher energies due to confinement-induced modifications in the electron density of states. Damping in bulk plasmons primarily occurs through Landau damping in semiconductors, where the collective mode decays into single-particle electron-hole pairs within the conduction band, and via interband transitions in metals, involving excitations across the band gap.^[18] These mechanisms result in shorter lifetimes for volume plasmons compared to localized surface modes, as the larger phase space in the bulk allows more decay channels.

Fabrication and Materials

Synthesis Techniques

Synthesis techniques for nanostructures supporting localized surface plasmons primarily involve chemical, physical, and assembly-based methods, enabling the creation of noble metal nanoparticles and arrays with tailored plasmonic properties.^[19] Chemical synthesis methods, particularly wet chemistry approaches, are widely used for producing colloidal plasmonic nanoparticles due to their simplicity and control over size and shape. The Turkevich method, involving the reduction of gold salts with sodium citrate, yields spherical gold nanoparticles typically 10-20 nm in diameter, stabilized by citrate ligands that prevent aggregation and support localized surface plasmon resonances in the visible range.^[20] For anisotropic structures like nanorods, seed-mediated growth employs cetyltrimethylammonium bromide (CTAB) surfactants to direct the elongation of gold seeds in the presence of ascorbic acid as a mild reductant, achieving aspect ratios from 1.5 to 10 and tunable longitudinal plasmon resonances up to 1300 nm. These techniques allow high yields in solution, often reaching concentrations of 10^12 particles per mL, but require precise control of precursor ratios to minimize polydispersity.^[21] Physical fabrication methods provide precise patterning for substrate-bound plasmonic structures, complementing solution-based approaches. Electron-beam lithography enables the creation of sub-10 nm resolution arrays of gold or silver nanoparticles, ideal for periodic plasmonic metasurfaces, though it is limited to small areas due to serial processing.^[22] Nanosphere lithography, using self-assembled polystyrene spheres as masks followed by metal deposition and etching, fabricates triangular nanoparticle arrays with uniform spacing, supporting collective plasmon modes in 2D lattices.^[19] Oblique angle vapor deposition, a physical vapor technique, grows tilted nanorods of silver or gold at grazing incidence angles (>75°), producing aligned arrays with enhanced light trapping for plasmonic applications.^[23] Laser ablation in liquids generates ligand-free nanoparticles by pulsing a focused laser on a metal target submerged in solvent, yielding clean gold or silver colloids with sizes 5-50 nm and minimal chemical residues.^[24] Colloidal assembly techniques organize pre-synthesized nanoparticles into ordered arrays to enhance plasmonic coupling. The Langmuir-Blodgett method compresses a monolayer of gold nanoparticles at the air-water interface and transfers it onto substrates, forming 2D hexagonal arrays with interparticle distances tunable via compression, which exhibit collective plasmon resonances shifted from isolated particles.^[25] DNA origami enables precise positioning of multiple gold nanoparticles into complex geometries, such as rings or chiral helices, using DNA scaffolds to control nanometer-scale spacing and achieve Fano-like or circular dichroism in plasmonic responses.^[26] Scalability remains a key challenge in plasmonic nanoparticle production, transitioning from lab-scale batch reactions to industrial volumes while maintaining uniformity. Wet chemical methods scale via continuous flow reactors, but issues like polydispersity (>10% variation) and impurity incorporation hinder reproducibility at gram-scale outputs.^[27] Physical techniques like nanosphere lithography offer roll-to-roll compatibility for large-area films, yet high costs and low throughput limit adoption beyond prototypes.^[28] Post-synthesis modifications, such as ligand exchange, enhance stability and functionality of plasmonic nanoparticles. Replacing CTAB with thiolated polyethylene glycol ligands improves biocompatibility and dispersibility in aqueous media, preserving plasmon resonances while enabling biomolecular conjugation for targeted applications.^[29] These surface functionalizations typically involve mild incubation steps, achieving near-complete coverage without significant aggregation.^[30]

Key Materials and Structures

Noble metals, particularly gold and silver, serve as the cornerstone materials for localized surface plasmons (LSPs) due to their negative real permittivity in the visible and near-infrared spectral regions, enabling strong light confinement at the nanoscale.^[31] The optical constants of these metals, including complex permittivity values essential for modeling LSP resonances, were experimentally measured by Johnson and Christy through reflection and transmission spectroscopy on thin films.^[32] For spherical gold nanoparticles, the LSP resonance typically peaks at approximately 520 nm in air, a wavelength that aligns well with common excitation sources and benefits from gold's chemical stability and biocompatibility, allowing integration into biological systems without significant toxicity.^[1] In contrast, silver nanoparticles exhibit a sharper LSP resonance around 400 nm, offering a higher quality factor due to lower intrinsic damping losses compared to gold, though silver's susceptibility to oxidation limits its long-term stability in ambient environments.^[33] Aluminum nanoparticles support LSP resonances in the ultraviolet range (around 200-300 nm), providing access to UV applications such as deep-UV sensing and lithography, despite challenges with oxidation that can be mitigated through protective coatings.^[34] Beyond noble metals, alternative materials have emerged to extend LSP functionality into new spectral ranges or improve compatibility with specific applications. Doped semiconductors, such as heavily doped silicon, support LSPs by tuning the plasma frequency through dopant concentration, achieving resonances in the near- to mid-infrared where noble metals underperform.^[35] Metal-halide perovskites are often enhanced by incorporating plasmonic metal nanoparticles, leading to improved photophysical properties through interactions between localized surface plasmons and polaritonic effects, with tunable responses via composition or structural modifications.^[36] Dielectric-metal hybrids, combining high-index dielectrics like silicon with thin metal layers, facilitate tunable LSP resonances by leveraging interference and hybridization, often shifting peaks across the visible to near-infrared for enhanced control.^[37] Key nanostructures that enable LSP properties include spheres, rods, core-shell configurations, and metasurfaces, each offering distinct resonance characteristics. Spherical nanoparticles primarily support dipole Mie resonances, providing a baseline for understanding LSP behavior in isotropic systems.^[38] Nanorods introduce anisotropy, with the longitudinal plasmon mode tunable from 600 to 800 nm depending on aspect ratio, allowing polarization-sensitive responses.^[39] Core-shell nanostructures promote plasmon hybridization between inner and outer interfaces, resulting in symmetric and antisymmetric modes that split the resonance for broader spectral coverage.^[40] Metasurfaces, arrays of subwavelength plasmonic elements, exhibit collective effects such as lattice-induced hybridization, enabling engineered responses like Fano resonances or beam steering.^[38] The LSP resonance wavelength is highly sensitive to nanoparticle size and shape, permitting tuning from the ultraviolet to near-infrared regions to match desired optical windows. For instance, increasing the diameter of gold spheres red-shifts the resonance by tens of nanometers, while elongating particles into prolate spheroids induces shifts of approximately 100 nm per unit increase in aspect ratio due to enhanced longitudinal field alignment.^[41] Environmental factors, particularly the refractive index of the surrounding medium or substrate, further modulate the resonance; for gold nanoparticles, immersion in water (refractive index 1.33) versus air (1.00) typically causes a positive shift of about 50 nm, reflecting the increased effective permittivity around the particle.^[42]

Characterization Methods

Optical Spectroscopy

Optical spectroscopy plays a central role in characterizing localized surface plasmon resonances (LSPRs) by measuring the interaction of light with plasmonic nanostructures, particularly through extinction and scattering spectra that reveal resonance peaks arising from the collective oscillation of electrons. UV-Vis extinction spectroscopy is a primary technique for probing LSPRs in ensembles of nanoparticles, where the extinction spectrum combines absorption and scattering contributions, typically showing a prominent peak in the visible range for noble metals like gold and silver. For instance, in colloidal solutions of silver nanoparticles, the LSPR peak around 400 nm shifts with particle size and surrounding medium refractive index, enabling sensitive detection of environmental changes. In hybrid systems combining plasmonic metals with semiconductors or dielectrics, the extinction spectra often exhibit Fano-like asymmetric profiles due to interference between the broad LSPR and narrow discrete transitions, as observed in gold nanorods coupled to quantum dots.^[43]^[44] Dark-field microscopy extends these measurements to single nanoparticles by selectively detecting scattered light, allowing the acquisition of scattering spectra that isolate the LSPR response without absorption interference. This technique reveals particle-to-particle variations in resonance wavelength and linewidth, particularly for anisotropic shapes like rods or triangles, where the scattering intensity and peak position depend on the polarization of the incident light relative to the particle's orientation. For example, gold nanorods exhibit distinct longitudinal and transverse LSPR modes, with polarization-aligned excitation enhancing the longitudinal mode scattering by factors of 10 or more compared to perpendicular orientations. Such single-particle spectra are typically narrower (full width at half maximum ~50-100 nm) than ensemble averages, highlighting shape-induced heterogeneity.^[45]^[46] Near-field optical methods provide spatial resolution beyond the diffraction limit to map local electromagnetic fields associated with LSPRs. Scanning near-field optical microscopy (SNOM), particularly the scattering-type variant (s-SNOM), uses a nanoscale tip to probe and image the near-field intensity distributions around plasmonic structures, revealing hotspots with enhancements up to 10^3-10^4 times the incident field. Tip-enhanced Raman spectroscopy (TERS), which leverages LSPR excitation at the tip-sample junction, achieves chemical specificity by amplifying Raman signals from molecules in the near field, with enhancement factors reaching up to 10^4 for analytes adsorbed on silver or gold tips. These techniques are essential for visualizing field confinement in subwavelength volumes, such as at the edges of triangular nanoparticles.^[47]^[48] Time-resolved spectroscopy uncovers the ultrafast dynamics of LSPRs, including electron dephasing and hot carrier generation. Pump-probe techniques, where a femtosecond pump pulse excites the LSPR and a delayed probe measures transient changes in transmission or reflection, reveal hot electron lifetimes on the order of 100 fs in gold nanoparticles, governed by electron-electron and electron-phonon scattering. These measurements quantify the relaxation cascade: initial dephasing in ~10-100 fs, followed by thermalization in picoseconds, which is critical for applications involving hot carrier injection. In hybrid metal-semiconductor systems, such dynamics show prolonged hot electron lifetimes up to several picoseconds due to transfer to the adjacent material.^[49]^[50] A key distinction in optical spectroscopy of LSPRs lies between ensemble and single-particle approaches, as colloidal ensembles average over size, shape, and environmental heterogeneities, broadening the apparent LSPR linewidth by 2-5 times compared to individual particles. For example, a 50 nm gold nanosphere ensemble might show a resonance at 520 nm with a width of 100 nm, while single-particle dark-field spectra reveal peaks as narrow as 40 nm, exposing distributions that mask subtle shifts in bulk measurements. Single-particle statistics, often collected from hundreds of nanoparticles via hyperspectral imaging, are vital for deconvoluting these effects and correlating optical response with structural variations observed via complementary techniques like scanning electron microscopy.^[51]^[46]

Structural and Morphological Analysis

Transmission electron microscopy (TEM) is widely employed to investigate the internal structure of plasmonic nanostructures, enabling visualization of core-shell configurations and crystalline defects in materials such as gold or silver nanoparticles. High-resolution TEM (HRTEM) further reveals lattice fringes, providing atomic-scale insights into the crystallographic orientation and grain boundaries that influence plasmonic behavior. Scanning transmission electron microscopy combined with electron energy-loss spectroscopy (STEM-EELS) offers nanoscale mapping of localized surface plasmons, achieving spatial resolutions approaching 1 nm by correlating energy losses with plasmon excitations in individual nanoparticles. Scanning electron microscopy (SEM) excels in characterizing the surface topography and morphological uniformity of plasmonic nanostructure arrays, such as lithographically patterned gold nanorods or nanoparticle films, by providing three-dimensional-like images of feature shapes and spacing. When coupled with energy-dispersive X-ray spectroscopy (EDX), SEM delivers compositional analysis, identifying elemental distributions like silver or copper in alloyed plasmonic systems to assess purity and homogeneity.^[52] Atomic force microscopy (AFM) provides precise height profiles and surface roughness measurements for plasmonic nanoparticles and thin films, quantifying dimensions that are critical for understanding geometry-dependent plasmon resonances. In tapping mode, AFM also probes mechanical properties, such as Young's modulus, of nanostructures like silver nanocubes, while correlative studies link topographic data to optical spectra for validating plasmon mode assignments.^[53] X-ray techniques complement electron-based methods for ensemble characterization; small-angle X-ray scattering (SAXS) determines size distributions and shapes of colloidal plasmonic nanomaterials, such as gold nanorods, by analyzing scattering patterns from thousands of particles in solution. Grazing-incidence small-angle X-ray scattering (GISAXS) is particularly useful for thin-film plasmonic structures, revealing in-plane ordering and layer thicknesses in supported nanoparticle arrays. Quantitative metrics, including aspect ratios and polydispersity indices, are derived from image analysis software applied to TEM, SEM, or AFM datasets, enabling statistical evaluation of nanostructure variability; for instance, aspect ratios greater than 3 in gold nanorods correlate with red-shifted plasmon peaks, while polydispersity indices below 0.1 indicate high monodispersity essential for reproducible optical responses. These morphological parameters often correlate briefly with observed optical spectra to refine models of plasmonic performance.^[52]

Applications and Emerging Uses

Biosensing and Detection

Localized surface plasmon resonance (LSPR) biosensing exploits the sensitivity of the plasmon resonance to changes in the local refractive index near the nanoparticle surface, where biomolecular binding events induce a shift in the resonance wavelength, typically Δλ ≈ 10–200 nm per refractive index unit (RIU). This sensitivity arises primarily from the enhanced electromagnetic fields at the nanoparticle surface, which amplify the optical response to analyte adsorption within a detection volume of about 5–10 nm.^[54]^[55] Nanobiosensors based on LSPR often employ gold nanorod arrays for detecting proteins such as prostate-specific antigen (PSA), achieving limits of detection down to ~1 aM through resonance shifts upon specific binding.^[56] Multiplexed detection is enabled by shape-encoded particles, where nanorods of varying aspect ratios produce distinct resonance wavelengths, allowing simultaneous identification of multiple analytes via spectral analysis.^[57] Label-free detection facilitates real-time monitoring of binding kinetics without fluorescent tags, with the figure-of-merit (FOM = S/Δω, where S is sensitivity and Δω is the resonance linewidth) reaching up to 10 in optimized designs that minimize damping losses.^[58] Integration of LSPR sensors with microfluidics has advanced lab-on-chip devices for point-of-care applications, such as the detection of SARS-CoV-2 viral antigens in clinical samples, with post-2020 developments enabling rapid assays in under 30 minutes at sensitivities below 0.1 ng/mL.^[59] As of 2025, emerging LSPR-based plasmonic nanostructures have enabled high-sensitivity exosome biosensing for cancer diagnostics, achieving femtomolar detection limits through synergistic PSPR and LSPR mode coupling.^[60] However, practical limits include noise from environmental fluctuations like temperature or bulk refractive index variations, which can broaden the resonance and reduce resolution; improvements via Fano resonances in nanostructured arrays narrow the linewidth to enhance signal-to-noise ratios and boost overall FOM.^[61]^[62]

Enhanced Light-Matter Interactions

Localized surface plasmons (LSPs) significantly enhance light-matter interactions by confining electromagnetic fields to nanoscale volumes, leading to amplified optical responses in various spectroscopic techniques. One prominent example is surface-enhanced Raman scattering (SERS), where LSPs in metallic nanoparticles boost Raman signals through both electromagnetic and chemical mechanisms. The electromagnetic mechanism arises from the intense local electric fields near the nanoparticle surface, particularly at "hotspots" formed in nanoparticle dimers with gaps of approximately 1-2 nm, achieving enhancement factors ranging from 10^6 to 10^10.^[63]^[64] The chemical mechanism involves charge transfer between the metal surface and adsorbed molecules, further increasing the polarizability and Raman cross-section by factors of 10^2 to 10^4.^[65] These combined effects enable single-molecule detection, with hotspots in silver nanocube dimers yielding enhancements up to 2 × 10^7.^[63] Plasmon-enhanced fluorescence (PEF) represents another key interaction, where LSPs increase the quantum yield and excitation rates of fluorophores by modifying the local density of optical states. Enhancements up to 1000-fold have been reported, particularly with aluminum metasurfaces featuring hybrid multipolar plasmons, allowing broadband visible fluorescence boosting for multiplexed biosensing.^[66] The enhancement exhibits strong distance dependence, with optimal fluorophore-plasmon separation of 5-10 nm to balance excitation enhancement and quenching effects; closer distances lead to non-radiative energy transfer, while farther ones reduce field intensity.^[67] This tunability is crucial for applications in high-sensitivity imaging, where gold nanoparticle substrates achieve up to 1000-fold emission increases at tuned separations.^[68] In nonlinear optics, LSPs amplify second-harmonic generation (SHG) by enhancing local fields that drive the quadratic nonlinear response in non-centrosymmetric materials or interfaces. The local field intensification, often by factors exceeding 10^4, converts incident light to its second harmonic with efficiencies boosted by several orders of magnitude in plasmonic nanostructures like gold nanoprisms.^[69] This plasmon-enhanced SHG is particularly valuable for bioimaging, providing label-free contrast in tissues without photobleaching, as demonstrated in SHG microscopy of biological samples where plasmonic substrates increase signal intensity for deeper penetration.^[70] LSP decay also generates hot electrons through non-radiative Landau damping, producing energetic carriers with energies up to several electron volts from visible light absorption. These hot electrons, arising from intraband and interband transitions in metals like gold and silver, enable photocatalysis by injecting into adjacent semiconductors, driving redox reactions with quantum efficiencies far exceeding linear absorption limits.^[71] Seminal studies highlight how LSPs in noble metal nanostructures produce hot electrons for applications in CO2 reduction and water splitting, with carrier lifetimes on the femtosecond scale before thermalization.^[72] Metamaterial designs incorporating epsilon-near-zero (ENZ) modes further tailor these interactions for broadband enhancement. ENZ conditions, where the real part of the permittivity approaches zero, lead to extreme field confinement and slow-light effects, coupling effectively with LSPs in hybrid structures like plasmonic nanorods on ENZ waveguides to create resonant modes with enhanced light-matter coupling over wide spectral ranges.^[73] Such designs achieve uniform field enhancements across visible and near-infrared wavelengths, enabling applications in nonlinear optics and sensing without the narrowband limitations of isolated LSPs.^[74]

Energy Conversion and Harvesting

Localized surface plasmons (LSPs) enable efficient energy conversion and harvesting by generating hot carriers and intense local fields that drive photochemical and photothermal processes. In plasmonic nanostructures, incident light excites collective electron oscillations, leading to non-radiative decay that produces energetic hot electrons and holes, as well as localized heating. These effects surpass the limitations of traditional semiconductors by harvesting sub-bandgap photons and enhancing charge separation, making LSPs promising for sustainable energy applications.^[75] In plasmonic solar cells, hot carrier injection from metal nanoparticles into adjacent semiconductors boosts photocurrent and overall efficiency. For instance, gold nanoparticles integrated into perovskite solar cells facilitate hot electron transfer, increasing power conversion efficiency (PCE) from 10.8% to 13.5%, a relative gain of approximately 25%.^[76] Similar enhancements occur in silicon-based devices, where antenna-reactor configurations—combining plasmonic light-harvesting antennas with catalytic reactors—improve hot carrier collection, yielding efficiency improvements of 20-30% over bare silicon through better infrared absorption and reduced recombination losses.^[77]^[78] As of 2024, plasmonic integrations in perovskite photovoltaics have contributed to single-junction efficiencies exceeding 25%, with LSPR enhancing near-infrared absorption in tandem configurations reaching over 30%.^[79]^[80] These designs leverage the Schottky barrier at metal-semiconductor interfaces to selectively inject hot electrons above the conduction band edge.^[76] Photothermal conversion exploits LSP-induced absorption to generate localized heat for applications like solar steam generation. Nanoparticle films, such as silver nanoparticles on diatomite substrates, achieve solar-to-steam efficiencies exceeding 90% under one-sun illumination by confining heat to the particle surface and minimizing losses to the bulk medium. Gold nanoflower-based hydrogels similarly demonstrate over 85% efficiency, enabling rapid vaporization rates suitable for desalination and water purification. These systems benefit from the broadband absorption of LSPs, which concentrates solar energy into nanoscale hotspots with temperature rises up to hundreds of degrees Celsius.^[76] Photocatalysis is advanced by hot electrons from LSP decay, which overcome wide bandgaps in semiconductors to drive reactions like water splitting and CO₂ reduction. In Au-TiO₂ heterostructures, plasmonic hot electrons inject into TiO₂, enhancing hydrogen evolution rates by up to 10 times compared to pristine TiO₂ under visible light, as seen in nanoparticle-decorated nanorods. Antenna-reactor setups further amplify this by coupling Au antennas to Pt reactors, achieving selective CO₂ conversion to methane with yields enhanced by localized field intensification. These mechanisms extend photocatalytic activity into the visible and near-infrared spectrum, critical for solar-driven fuel production.^[81] Thermoplasmonics harnesses the spatial temperature profiles around LSP resonators for precise thermal control. Gold nanoparticles embedded in polymer matrices create nanoscale gradients, enabling light-triggered drug release from carriers, where illumination causes rapid expansion and payload delivery with minimal collateral heating. This approach has been demonstrated in cellular environments, achieving controlled release efficiencies over 80% within seconds of near-infrared exposure.^[82] Despite these advances, challenges persist, including photostability under prolonged illumination, where metal oxidation and sintering degrade performance. Recent developments in the 2020s, such as alloy nanoparticles (e.g., Au-Ag core-shells), broaden absorption spectra and improve durability, enhancing PCE in solar cells to over 20% while maintaining catalytic activity. Ongoing research focuses on optimizing interfaces to minimize carrier recombination and extend operational lifetimes.^[76]

References

[1]
Developments in Localized Surface Plasmon Resonance
Nov 4, 2024 · Localized surface plasmon resonance (LSPR) is a nanoscale phenomenon associated with noble metal nanostructures that has long been studied and has gained ...
[2]
Review Localized surface plasmon resonance - ScienceDirect.com
Localized surface plasmon resonance (LSPR) is an optical phenomena generated by light when it interacts with conductive nanoparticles (NPs) that are smaller ...Missing: definition key
[3]
Localized Surface Plasmon - an overview | ScienceDirect Topics
Localized surface plasmon refers to the resonance of excited conduction electrons in metal nanoparticles when exposed to electromagnetic radiation, ...
[4]
Plasmonics: Localization and guiding of electromagnetic energy in ...
Jul 11, 2005 · After initial studies of the physics of these excitations, in the 1980s SPPs started to attract the attention of chemists, as the electric-field ...<|control11|><|separator|>
[5]
Localized Surface Plasmon Resonance Spectroscopy and Sensing
May 5, 2007 · Localized surface plasmon resonance (LSPR) spectroscopy of metallic nanoparticles is a powerful technique for chemical and biological sensing experiments.Missing: developments | Show results with:developments
[6]
Local Structure-Driven Localized Surface Plasmon Absorption and ...
Since the early 1990s, the optical properties of gold nanoparticles (NPs) have attracted renewed interest due to the rapid development ...
[7]
Theory Of Dielectrics : Frohlich H. - Internet Archive
Jan 21, 2017 · Theory Of Dielectrics. by: Frohlich H. Publication date: 1949. Topics: C-DAC. Collection: digitallibraryindia; JaiGyan. Language: English. Item ...
[8]
[PDF] SAND78-6018-Mie-1908-translation.pdf - ScattPort
This document is a translation of G. Mie's 1908 work on the optics of turbid media, specifically colloidal metal solutions.
[9]
Gans, R.: Über die Form ultramikroskopischer Goldteilchen. Ann ...
Aug 7, 2025 · In 1912, Gans extended the concept of Mie's theory to anisotropic nanoparticles absorbing light in a more extended wavelength range, as ...
[10]
Plasma Losses by Fast Electrons in Thin Films | Phys. Rev.
In thin films, energy loss by fast electrons can occur at or below plasma energy, and increases per unit thickness as foil thickness decreases.Missing: plasmons | Show results with:plasmons
[11]
Excitation of nonradiative surface plasma waves in silver by the ...
Excitation of nonradiative surface plasma waves in silver by the method of frustrated total reflection. Published: 01 August 1968. Volume 216, pages 398–410, ( ...
[12]
https://www.degruyter.com/document/doi/10.1515/zna-1968-1247/html
[13]
Propagation length of surface plasmon polaritons determined by ...
Jan 12, 2010 · The radiative loss depends on the slope of the edge sidewall and on the wafer oxide thickness, both of which must be considered when reconciling ...
[14]
Propagating and localized surface plasmon resonance sensing
This paper provides a critical comparison of these kinds of SPR sensing, reviews the foundation of both general approaches, presents experimental data
[15]
Wave-mechanical and second-quantized theories | Phys. Rev. A
Jun 1, 2021 · BULK PLASMONS. In this section we establish and discuss the first- and second-quantized theory of bulk plasmons. Starting from the plasmon ...
[16]
volume plasmon | Glossary | JEOL Ltd.
The volume plasmon is directly observed as a peak in an electron energy-loss spectrum. It should be noted that the volume plasmon cannot be excited nor can be ...Missing: polaritons definition
[17]
Surface and volume plasmons in metallic nanospheres in a ...
Jul 15, 2010 · The damping-caused plasmon resonance shifts are compared with the experimental data for metallic nanoparticles of different sizes located in a ...
[18]
Role of nonlocality and Landau damping in the dynamics of a ...
The corresponding damping rate rises linearly with the plasmon wave vector, so that the contribution of the Landau damping increases, becoming the largest ...
[19]
Nanosphere Lithography: A Versatile Nanofabrication Tool for ...
Methods for deposition of a nanosphere solution onto the desired substrate include spin coating,77 drop coating, 78 and thermoelectrically cooled angle coating.
[20]
Turkevich in New Robes: Key Questions Answered for the Most ...
Jul 6, 2015 · This contribution provides a comprehensive mechanistic picture of the gold nanoparticle synthesis by citrate reduction of HAuCl 4 , known as Turkevich method.<|separator|>
[21]
Seed-Mediated Synthesis of Gold Nanorods at Low Concentrations ...
Mar 24, 2021 · Here, we report the seed-mediated growth of AuNRs at very low concentrations of CTAB (as low as 0.008 M, ∼20% of that in the previous work (16)) ...
[22]
(PDF) Nanofabrication for Plasmonics - ResearchGate
Aug 10, 2025 · This paper aims at giving a comprehensive overview of the different nanofabrication techniques used in plasmonics including focused electron- ...
[23]
Oblique angle deposition and its applications in plasmonics
Jul 8, 2013 · Oblique angle deposition (OAD) has been demonstrated as a powerful technique for various plasmonic applications due to its advantages in controlling the size, ...Missing: vapor | Show results with:vapor
[24]
Laser ablation in liquids for nanomaterial synthesis - IOP Science
Aug 23, 2021 · This review gives a comprehensive summary of the nanomaterials synthesized by LAL using different types of target and liquid, with an emphasis on the effects ...
[25]
Structural characterization and plasmonic properties of two ...
May 15, 2017 · Two-dimensional (2D) arrays of the AuNPs were obtained by Langmuir-Blodgett method with polyethylene glycol. •. The plasmon resonant ...
[26]
Plasmonic nanostructures through DNA-assisted lithography - Science
Feb 2, 2018 · We report a DNA-assisted lithography (DALI) method that combines the structural versatility of DNA origami with conventional lithography techniques.
[27]
Recent Developments in Automated Reactors for Plasmonic ... - NIH
Scalability remains a significant challenge for both batch and continuous flow synthesis.
[28]
Development of controlled nanosphere lithography technology
Feb 27, 2023 · This work is devoted to the development of nanosphere lithography (NSL) technology, which is a low-cost and efficient method to form nanostructures for ...
[29]
Ligands of Nanoparticles and Their Influence on the Morphologies ...
This review discusses the effects of various ligand types on the morphology and performance of nanoparticle-based films<|control11|><|separator|>
[30]
Heterogeneous Kinetics in the Functionalization of Single Plasmonic ...
Therefore, plasmonic nanoparticles enable detection of ssDNA binding to the surface of the particle by probing time-dependent plasmon resonance shifts. To probe ...
[31]
Localized Surface Plasmon Resonance Biosensing: Current ... - MDPI
The most common materials used are gold and silver, although other metals such as copper and aluminum also exhibit plasmon resonance. When the incident ...
[32]
The importance of accurate determination of optical constants for the ...
This work documents several optical constant sources for silver, aluminium, gold and titanium, and the effect this has on plasmon quality factors. The effect of ...
[33]
[PDF] Alternative Plasmonic Materials for Biochemical Sensing: A Review
Sep 14, 2024 · We cover a wide variety of plasmonic material platforms, such as transparent conductive oxides, nitrides, doped semiconductors, polar materials, ...
[34]
Metal-Halide Perovskite Semiconductors Can Compete with Silicon ...
Oct 26, 2021 · Metal-halide perovskite semiconductors can compete with silicon counterparts for solar cells, LEDs. Road map for organic-inorganic hybrid perovskite ...
[35]
Dielectric Nanowire Hybrids for Plasmon-Enhanced Light-Matter ...
Herein, we propose a dielectric nanostructure for plasmon-enhanced light-matter interaction of TMDs. TiO2 nanowires (NWs), as an example, are hybridized with ...
[36]
Nanostructures for surface plasmons - Optica Publishing Group
Resonance frequencies or wavelengths of SPs can be tuned by design of metal nanostructures, such as nanoparticles, nanorods, nanowires, nanosheets, and ...
[37]
Size-dependent optical properties of Au nanorods - ScienceDirect.com
From the figure it is clear that the increase in reductant concentration red-shifts the LSPR to longer wavelength region indicating an increase in aspect ratio ...
[38]
Plasmonic Core–Shell Nanoparticle Enhanced Spectroscopies for ...
These nanostructures serve as optical antennae (11) receiving and confining photons which cause electronic oscillations known as surface plasmons that can ...
[39]
Shape-Dependent Field Enhancement and Plasmon Resonance of ...
Mar 5, 2015 · The direct dependence of the sensitivity on the aspect ratio becomes more prominent as the size of nanorods becomes larger. However, the use ...
[40]
Refractive Index-Modulated LSPR Sensing in 20–120 nm Gold and ...
Nov 16, 2023 · Localized surface plasmon resonance (LSPR) based sensing has been a simple and cost-effective way to measure local refractive index changes.
[41]
Localized Surface Plasmon Resonance Spectroscopy of Triangular ...
The localized surface plasmon resonance (LSPR) of Al nanoparticles fabricated by nanosphere lithography (NSL) was examined by UV−vis extinction spectroscopy ...Introduction · Experimental Methods · Results and Discussion · Conclusions
[42]
Subradiant LSPR Sensing and a Tunable Fano Resonance
Symmetry breaking in this structure enables a coupling between plasmon modes of differing multipolar order, resulting in a tunable Fano resonance.Missing: profiles | Show results with:profiles
[43]
Single Particle Plasmonics for Materials Science ... - ACS Publications
May 8, 2019 · (a) Schematic depiction of the dark-field scattering microscopy principle. (b) True-color dark-field microscopy image of electron beam ...Figure 1 · Figure 6 · Future Perspectives
[44]
Multispectral Localized Surface Plasmon Resonance (msLSPR ...
Jan 19, 2023 · We report multispectral LSPR (msLSPR), a wide-field imaging technique for real-time spectral monitoring of light scattering from individual nanoparticles.<|control11|><|separator|>
[45]
Tuning Localized Surface Plasmon Resonance in Scanning Near ...
A reproducible route for tuning localized surface plasmon resonance in scattering type near-field optical microscopy probes is presented.
[46]
Tip-Enhanced Raman Spectroscopy | Analytical Chemistry
Aug 29, 2016 · The TERS enhancement factor is modified as (5)where EN(r0, ω) is the modified local field, when considering the plasmonic near field self- ...Novel Technique: TERS · TERS Samples and Tips · Recent Advances Regarding...
[47]
Review of Plasmon-Induced Hot-Electron Dynamics and Related ...
Dec 20, 2016 · The hot-electron lifetimes can be measured using time-resolved ... are performed using an optical time-resolved pump-probe technique ...
[48]
Confined Hot Electron Relaxation at the Molecular Heterointerface ...
Jan 7, 2021 · The time-resolved pump–probe measurements demonstrate that plasmon dephasing generates hot electrons which undergo electron–electron scattering.
[49]
Single-Particle Spectroscopy Reveals Heterogeneity in ...
Jun 27, 2014 · A hyperspectral imaging method was developed that allowed the identification of heterogeneous plasmon response from 50 nm diameter gold colloidal particles.
[50]
Exploring Coupled Plasmonic Nanostructures in the Near Field by ...
Oct 24, 2016 · The extraordinary optical properties of coupled plasmonic nanostructures make these materials potentially useful in many applications; thus, ...
[51]
Near-field and SERS enhancement from rough plasmonic ...
However, AFM allows us to measure a quantitative height profile of the particles, which can be used to build a geometric model of the particles (see below). ...
[52]
Localized Surface Plasmon Resonance Biosensing - NIH
The first section gives a general background to the physical origin of LSPR and factors that affect the observed LSPR response. The next several sections ...Missing: definition | Show results with:definition
[53]
Local Refractive Index Sensitivity of Localized Surface Plasmon ...
Nov 4, 2024 · The sensitivity of localized surface plasmon resonance (LSPR) biosensors to a change in the local refractive index (RI) is investigated theoretically.
[54]
Rational aspect ratio and suitable antibody coverage of gold ...
Mar 21, 2012 · When using individual Au nanorod sensors for the detection of prostate specific antigen (PSA), the lowest concentration recorded was ~1 aM (~6 × ...
[55]
[PDF] Gold nanorod-based localized surface plasmon resonance biosensors
As metallic nanoparticles of different sizes and shapes possess different LSPR absorption bands, multiplexed LSPR biosensing can be realized by employing ...Missing: encoded | Show results with:encoded<|control11|><|separator|>
[56]
https://pubmed.ncbi.nlm.nih.gov/22298159/
[57]
Detection of antibodies against SARS-CoV-2 spike protein by gold ...
An opto-microfluidic chip using gold nanospikes and LSPR detects SARS-CoV-2 antibodies in plasma within 30 minutes, with a limit of detection of 0.08 ng/mL.Missing: post- | Show results with:post-
[58]
Seeing protein monolayers with naked eye through plasmonic Fano ...
Jun 29, 2011 · We introduce an ultrasensitive label-free detection technique based on asymmetric Fano resonances in plasmonic nanoholes with far reaching implications for ...
[59]
High-sensitivity plasmonic sensor by narrowing Fano resonances in ...
Jun 22, 2021 · We experimentally obtain a narrow Fano resonance with a linewidth of Δλ = 2.5 nm, which is greater than the simulation results (∼1.1 nm) because ...
[60]
Measuring the SERS Enhancement Factors of Dimers with Different ...
The highest SERS enhancement factors were found for face-to-face (2.0x10^7) and edge-to-face (1.5x10^7) silver nanocube dimers, while edge-to-edge was 5.6x10^6.
[61]
Calculated enhancement factors of surface enhanced Raman ...
The total enhancement factor for SERS is the simple product of chemical enhancement and electromagnetic enhancement factors, it might be achieved up to 10 ...<|control11|><|separator|>
[62]
Surface enhanced Raman scattering revealed by interfacial charge ...
Oct 13, 2020 · Regarding charge-transfer-induced SERS enhancements, this short review introduces the basic concepts underlying the SERS enhancements, the most ...<|control11|><|separator|>
[63]
Aluminum Metasurface with Hybrid Multipolar Plasmons for 1000 ...
Nov 5, 2019 · Aluminum Metasurface with Hybrid Multipolar Plasmons for 1000-Fold Broadband Visible Fluorescence Enhancement and Multiplexed Biosensing.
[64]
Distance dependence of plasmon-enhanced fluorescence and ...
The study found that the optimal distance for maximum plasmon enhancement of Eosin luminescence is 6-8 nm, causing increased intensity and decreased lifetimes.
[65]
[PDF] Surface Plasmon Enhanced Fluorescence for Biological Imaging
... enhancement factor as a function of the emission wavelength using the data in Figure 5.1b and Figure 5.1d. A maximum enhancement factor of >1000 is achieved at.
[66]
Nonlinear plasmonics: second-harmonic generation and ... - PhotoniX
Oct 5, 2023 · In this review, we give insights into fundamental roles dominating the radiations of such nonlinear optical processes and their recent research advances.
[67]
Intermolecular interactions enhanced second harmony generation of ...
Feb 15, 2023 · Second harmonic generation (SHG) microscopy avoids the inherent drawbacks of traditional fluorescent probes and brings a major breakthrough ...
[68]
Localized surface plasmons and hot electrons - ScienceDirect.com
Dec 5, 2014 · By using localized surface plasmons to generate hot carriers in noble metal nanostructures, visible light can produce energetic electrons (or ...
[69]
Plasmon-Induced Hot Electrons in Nanostructured Materials
Jun 3, 2024 · The LSPR can decay through different channels: (1) radiative decay in the form of elastic scattering; (2) nonradiative resonant energy transfer, ...
[70]
Epsilon-near-zero media coupled with localized surface plasmon ...
Oct 5, 2020 · We demonstrate that a plasmonic nanostructure (nanorod) can be strongly coupled to the plasmonic waveguide, providing two new hybrid resonance modes.
[71]
Epsilon-Near-Zero Modes for Tailored Light-Matter Interaction
Oct 20, 2015 · In this work, we aim to tailor light-matter interactions at the nanoscale by using fundamental condensed-matter excitations such as plasmons and ...Missing: localized broadband
[72]
Plasmons for Energy Conversion - ACS Publications
May 31, 2018 · Plasmon-mediated electrocatalysis for sustainable energy: From electrochemical conversion of different feedstocks to fuel cell reactions.
[73]
Rational Design of Plasmonic Metal Nanostructures for Solar Energy ...
Jul 13, 2021 · Surface plasmons can maximize the utilization and conversion of solar energy and achieve redistribution of photons, electrons, and thermal ...
[74]
https://link.aps.org/doi/10.1103/PhysRevApplied.4.044011
[75]
Heterometallic antenna−reactor complexes for photocatalysis - PNAS
Jul 21, 2016 · Here we show that coupling a plasmonic nanoantenna directly to catalytic nanoparticles enables the light-induced generation of hot carriers within the catalyst ...
[76]
Recent Advances in Plasmonic Photocatalysis Based on TiO2 and ...
Aug 15, 2021 · This review aims to comprehensively summarize the fundamentals and to provide the guidelines for future work in the field of TiO 2 -based plasmonic ...
[77]
Biological Applications of Thermoplasmonics | Nano Letters
Plasmonic heating of nanoparticles is also being extensively investigated in the field of drug delivery for light-triggered release of therapeutic molecules, ...