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Ag nanocrystals with nearly ideal optical quality: synthesis, growth mechanism, and characterizations
摘要： Though Ag nanocrystals are predicted as the best material for localized surface plasmon resonances (LSPR) in the visible light region, realization of their ideal LSPR properties is hindered by the stringent requirement, i.e., simultaneous control of their size, shape, crystallinity, and surface structure. To achieve this goal, a synthetic scheme in non-polar solvent coupled with mild oxidative-etching by H+ ions is established. With a trace amount of Cl- ions as catalysts, H+ ions (in the form of carboxylic acids) become active for selectively etching the nuclei (and small nanocrystals) with imperfect crystal structure, which results in a new growth mechanism for formation of monodisperse nanocrystals, namely “self-focusing of size/crystallinity distribution”. H+ ions, ligands, and other reagents in the scheme are confirmed to possess negligible effects on the surface dielectric properties of Ag nanocrystals. To eliminate radiative damping of LSPR, single-crystalline and monodisperse spherical Ag nanocrystals in the size range between 7 and 20 nm are synthesized using this one-pot scheme. With excellent control of all the structural parameters, the full-width-at-half-maximum of LSPR spectra of single-crystalline Ag nanocrystals match theoretical predictions in the entire size range, and the maximum quality factor (~20) of LSPR predicted by theory is realized. Raman enhancement factor of the single-crystalline Ag nanocrystals for crystal violet (excitation at 514 nm) is 5 times higher than that of the typical multi-twinned ones with the same size.
关键词： localized surface plasmon resonances,oxidative-etching,monodisperse,single-crystalline,Ag nanocrystals,Raman enhancement
更新于2025-09-23 15:21:21
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Nonperturbative nonlinear effects in the dispersion relations for TE and TM plasmons on two-dimensional materials
摘要： We analytically obtain the dispersion relations for transverse-electric (TE) and transverse-magnetic (TM) surface plasmon-polaritons in a nonlinear two-dimensional (2D) conducting material with inversion symmetry lying between two Kerr-type dielectric media. To this end, we use Maxwell’s equations within the quasielectrostatic, weakly dissipative regime. We show that the wavelength and propagation distance of surface plasmons decrease due to the nonlinearity of the surrounding dielectric. In contrast, the effect of the nonlinearity of the 2D material depends on the signs of the real and imaginary parts of the third-order conductivity. Notably, the dispersion relations obtained by naively replacing the permittivity of the dielectric medium by its nonlinear counterpart in the respective dispersion relations of the linear regime are not accurate. We apply our analysis to the case of doped graphene and make predictions for the surface plasmon wavelength and propagation distance.
关键词： Maxwell’s equations,quasielectrostatic regime,weakly dissipative regime,nonlinear two-dimensional materials,surface plasmon-polaritons,doped graphene,Kerr-type dielectric media
更新于2025-09-23 15:21:21
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Recent progress in all-fiber non-Gaussian optical beam shaping technologies
摘要： Rapid development of fiber lasers are being followed by wide ranges of applications in laser processing technologies. One of the key parameters to determine the laser-matter interaction is beam shape and there have been intense research activities on beam shaping using bulk-optics. However, fiber optic solutions would take clear advantages over bulk-optics especially for fiber laser sources in terms of the beam conversion efficiency, the throughput power, and the compact footprint. In this article, all-fiber optical beam shaping technologies are reviewed and they are categorized as the phase front modification on the fiber facet, the surface plasmonics on fiber, all-fiber Fourier transformation, and multimode interference. Their physical principles, beam shaping capability, and some of the novel applications are explained
关键词： Phase front engineering,Laser beam,Surface plasmon polariton,Beam Shaping,Multimode Interference,Fourier Transform,Fiber Optics,Single mode optical fiber
更新于2025-09-23 15:21:21
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Exploring the transfer squeezing properties from photons to the symmetric and asymmetric SPP modes
摘要： Quantum surface plasmon polariton (SPP) is a growing research area with many unknown phenomena. In this paper, the behavior of the squeezed SPP modes on the metal slab is assessed. To begin with, a quantized form of the SPP modes propagating on the metal thin film based on the Green’s tensor method is provided. Since the squeezing properties of the SPP modes are indeed transferred from incident photons, at the next step, different aspects of this phenomenon are studied. Obtaining an important direct relation between incident photons’ properties and SPP modes, will allow for the effective factors on this phenomenon to be explored. Although the initial quantum properties will be changed or lost during the photons- surface plasmon interaction, it will be shown that some factors can improve the transfer process. Finally, the squeezing transfer from incident photons to the SPP modes and effective factors on it as a full quantum phenomenon will be investigated.
关键词： squeezed SPP modes,quantum properties transfer,Quantum surface plasmon polariton,Green’s tensor method
更新于2025-09-23 15:21:21
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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz2018) - Nagoya, Japan (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - On the Contribution of Thermally Generated Surface Plasmon-Polaritons to Heat Radiation of Metal Objects
摘要： We present theoretical and experimental evaluations of the thermally generated surface plasmon polaritons (TSPPs) contribution to heat radiation of metal objects. It is found that this contribution is significant only for the edges of such objects flat facets observed at sliding angles to the facets planes and it is p-polarized. The analytical model for calculation the spectrum and the integral intensity of the entire set of TSPPs arriving to the edge of their sources line has been developed. In contrast to thermal radiation, intensity of TSPPs is proportional to the third rather than fourth degree of temperature, while the TSPP spectrum is shifted towards low frequencies relative to the thermal radiation spectrum.
关键词： thermally generated surface plasmon polaritons,metal objects,heat radiation,p-polarized,analytical model
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Generation of light beams by electron beam excited surface plasmons
摘要： Manipulation of Smith-Purcell radiation (SPR) by electron-bunch excitation of localized surface plasmon (LSP) of gold (Au) disc arrays on Au substrate is investigated by FDTD simulation. When the wavelength of LSP mode is within the SPR emission band, SPR is locked and enhanced at the LSP wavelength. The emission angle of LSP-locked SPR still follows the wavelength-angle relation of traditional SPR. Furthermore, both the emission wavelength and angle increase as the radius and height of Au disc increase.
关键词： FDTD simulation,Smith-Purcell radiation (SPR),localized surface plasmon (LSP)
更新于2025-09-23 15:21:21
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Heterogeneous photocatalyzed C-C cross-coupling reactions under visible-light and near-infrared light irradiation
摘要： With the development of photocatalytic technology and organic synthesis chemistry, the photocatalyzed cross-coupling reaction provides one of the most attractive methodologies for the C-C bond formation and has been booming in recent years. The advantages of the heterogeneous photocatalyzed C-C cross-coupling reaction lie in its environment friendly, easily separated and conveniently recovered catalysts. In this review, we summarized and highlighted recent achievements of heterogeneous photocatalyzed C-C cross-coupling reactions through four aspects: visible light induced C-C cross-coupling reactions catalyzed by Pd supported semiconductor photocatalysts; visible light induced C-C cross-coupling reactions catalyzed by Pd based plasmonic photocatalysts; visible light induced C-C cross-coupling reactions catalyzed by palladium-free photocatalysts; near-infrared light induced C-C cross-coupling reactions.
关键词： Photocatalysis,semiconductor,C-C cross-coupling,localized surface plasmon resonance,Pd
更新于2025-09-23 15:21:21
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Photothermal Effects Induced by Surface Plasmon Resonance at Graphene/Gold Nanointerfaces: A Multiscale Modeling Study
摘要： Surface plasmon resonance (SPR) biosensors have enormous potential in biological recognitions and biomolecular interactions, especially for the real time measurement of disease diagnosis and drug screening. Extensive efforts have been invested to ameliorate the sensing performances, while the photothermal effects, which are induced by the plasmon resonance, have an obvious impact. However, due to the limitations of experimental approaches, the theoretical mechanisms and specific influences of the SPR sensors with photothermal effects are few researched. Here, a multiscale simulation method is developed to investigate the photothermal effects at graphene/gold (Au) nanointerfaces, and to calculate the quantitative contribution of the photothermal effects towards high reliability SPR sensors in order to elucidate their influence on the sensing performances by means of first-principle calculations and molecular dynamics simulations. Our results indicate that the sensitivity and detection accuracy of graphene/Au SPR sensors can be tailored from 0 K to 600 K, due to the tunable dielectric constants of Au and graphene films through temperature variation. By controlling the its material thickness, interfacial combination and lattice strain, an optimized graphene/Au SPR sensor with higher sensitivity, detection accuracy, and reliability to the temperature rising has been achieved. Such multiscale simulation method, which is capable of seeking both the role and the underlying mechanism of the interfacial phenomena, can serve as an excellent guideline for the performance optimization and commercialized application of SPR sensors in the analytical chemistry and biomedical fields.
关键词： graphene/gold nanointerface,photothermal effects,surface plasmon resonance,multiscale simulation method,sensitivity and detection accuracy
更新于2025-09-23 15:21:21
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Near-field spatial frequency filtering model for surface plasmon self-interference virtual probe
摘要： The azimuthal angle relation for obliquely excited standing-wave surface plasmon is analytically studied in detail and thereby a near-field spatial frequency filtering model is proposed, in which the azimuthal angle relation and criterion similar to Heisenberg uncertainty principle are combined to describe the spatial resolving power of surface plasmon self-interference virtual probe imaging system. It is revealed that the incidence coupling possesses spatial anisotropy due to polarization modulation, and the mechanism for spatial resolution degradation is the compression of spatial frequency bandwidth in the near-field domain.
关键词： spatial frequency filter,virtual probe,surface plasmon self-interference
更新于2025-09-23 15:21:21
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A sensitive colorimetric probe for detection of 6-thioguanine based on its protective effect on the silver nanoprisms
摘要： In this work a non-aggregated colorimetric probe for detection of chemotherapeutic drug, 6–thioguanine (6-TG), is introduced. It is based on the protective effect of 6-TG on silver nanoprisms (AgNPRs) against the iodide-induced etching reaction. Iodide ions can attack the corners of AgNPRs and etch them, leading to the morphological transition from nanoprisms to nanodiscs. As a consequence, the solution color changes from blue to pink. However, in the presence of 6-TG, due to its protective effect on the corners of AgNPRs, I- ions cannot etch the prisms and the blue color of solution remains unchanged. Using this effect, selective sensor was designed for detection of 6–TG in the range of 2.5-500 μg L-1, with a detection limit of 0.95 μg L-1. Since with varying the concentration of 6-TG in this range, the color variation from pink to blue can be easily observed, the designed sensing scheme can be used as a colorimetric probe. The method was used for analysis of human plasma samples.
关键词： Anti-cancer drugs,Anisotropic nanoparticles,Surface plasmon resonance,Nanomaterials
更新于2025-09-23 15:21:21