共查询到20条相似文献,搜索用时 140 毫秒
1.
Lehmann J Merschdorf M Pfeiffer W Thon A Voll S Gerber G 《Physical review letters》2000,85(14):2921-2924
Multiphoton photoelectron spectroscopy reveals the multiple excitation of the surface plasmon in silver nanoparticles on graphite. Resonant excitation of the surface plasmon with 400 nm femtosecond radiation allows one to distinguish between photoemission from the nanoparticles and the substrate. Two different previously unobserved decay channels of the collective excitation have been identified, namely, decay into one or several single-particle excitations. 相似文献
2.
M. Merschdorf W. Pfeiffer A. Thon S. Voll G. Gerber 《Applied Physics A: Materials Science & Processing》2000,71(5):547-552
Two-photon photoemission spectroscopy using femtosecond laser pulses is used to investigate the excitation and decay mechanisms
of the surface plasmon resonance in Ag nanoparticles grown on graphite. The resonant excitation of this collective excitation
leads to a two-orders-of-magnitude-enhanced two-photon photoemission yield from a graphite surface with Ag nanoparticles compared
to the yield from pure graphite. From the shape of the photoemission spectra, the polarization dependence of the photoemission
yield and the excitation probabilities for different excitation pathways we conclude that excitation with 400-nm femtosecond
laser pulses leads to the coherent multiple excitation of the surface plasmon in the Ag nanoparticles. This multiply excited
plasmon mode can decay via the coupling to a single-particle excitation leading to the emission of an electron if its final
state is located in the continuum. The surface plasmon in metallic nanoparticles is a model system to investigate collective
excitations in multiphoton processes.
Received: 26 June 2000 / Accepted: 2 September 2000 / Published online: 12 October 2000 相似文献
3.
In this paper, enhanced fluorescence from a silver film coated nanosphere templated grating is presented. Initially, numerical
simulation was performed to determine the plasmon resonance wavelength by varying the thickness of the silver film on top
of a monolayer of 400 nm nanospheres. The simulation results are verified experimentally and tested for enhancing fluorescence
from fluorescein isothiocyanate whose excitation wavelength closely matches with the plasmon resonance wavelength of the substrate
with 100 nm silver film over nanosphere. The 12 times enhancement in the intensity is attributed to the local field enhancement
in addition to the excitation of surface plasmon polaritons along the surface. 相似文献
4.
G. Seifert M. Kaempfe K.-J. Berg H. Graener 《Applied physics. B, Lasers and optics》2000,71(6):795-800
Single-color femtosecond pump-probe experiments were performed to investigate the time dependence of laser-induced ultrafast
desorption and deformation processes of silver nanoparticles in glass. After laser excitation at wavelengths close to the
surface plasmon resonance, transient extinction changes were found to exhibit dynamics on quite different time scales ranging
from sub-picoseconds to some hundred ps. The slowest observed decay component is identified as characteristic for the deformation/desorption
processes. Possible mechanisms for these processes are discussed.
Received: 3 April 2000 / Revised version: 3 July 2000 / Published online: 20 September 2000 相似文献
5.
P. Scholz S. Schwieger B. Ashall D. Zerulla E. Runge 《Applied physics. B, Lasers and optics》2008,93(1):111-115
The influence of the nanowire shape on the excitation of surface plasmon polaritons at metallic nanowire arrays is studied
numerically. For a system of silver nanowires housed on a polymer substrate, nanowires with rectangular and elliptical cross
sections are compared. It was found that in the case of rectangular nanowires the excitation efficiency is higher for surface
plasmons at the polymer–metal interface than for surface plasmons at the air–metal interface. Conversely, in the case of elliptical
nanowires the air–metal plasmon modes are stronger. Further, it is noted that the nanowire shape directly influences the position
of the surface plasmon resonance. 相似文献
6.
Surface enhanced Raman scattering of pyridine adsorbed to weakly roughened silver films is studied using a well-characterized extended surface plasmon excitation. We show that the additional increase in the Raman signal associated with the extended surface plasmon is fully accounted for by the enhancement in the average macroscopic field. 相似文献
7.
We investigate the excitation of surface plasmon polaritons on silver tubes with finite-difference time-domain simulations. These surface plasmon polaritons exhibit azimuthal whispering gallery modes with quality factors in the hundreds. We show that the high quality factors arise from the coupling of the surface plasmon modes to photonic modes inside the tube. We examine the influence of a gain material on the quality factors and find that for material data of rhodamine 6G, the quality factors are enhanced significantly up to values of 3000. 相似文献
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10.
The optical excitation and decay of surface plasmons on Ag films is reported. The optical decay is observed as an annular cone of light when the substrate is in the form of a hemisphere. The polarization and angular distribution of this cone radiation is presented and compared to the roughness-coupled surface plasmon radiation simultaneously emitted from the Ag. 相似文献
11.
Yu Juan Zhang 《Journal of Quantitative Spectroscopy & Radiative Transfer》2012,113(8):578-581
The wavelength shift of surface plasmon resonance peak resulting from the electromagnetic coupling noble metal nanoparticle increases with the increase in the dielectric constant of the medium and the decrease in the interparticle separation distance. In this work, the discrete dipole approximation method was used to calculate the extinction efficiency spectra of the silver–silver and gold–gold nanoparticle pairs. This work shows that the silver coupled-particle system has higher plasmon resonance sensitivity as compared to the gold coupled-particle system. However, the silver coupled-particle system has lower and a faster near-exponential decay of sensitivity enhancement factor than the gold coupled-particle system. Thus, the silver coupled-particle may be more suited for sensing applications as compared to the gold coupled-particle, but the interparticle coupling effect displays more pronounced effect on the gold coupled-particle system as compared to the silver coupled-particle system. 相似文献
12.
Local field surface plasmon excitation of pair arrays of silver nanospheres was studied using three-dimensional finite-difference time-domain method. The near-field enhancement was associated with the radius of nanosphere and the incident wavelength, the highest of which always appeared in the penultimate gaps, regardless of the number of the pairs. The surface plasmon resonance could be controlled and tuned by radius of nanosphere and incident wavelength. 相似文献
13.
By combination of two special methods, i.e., persistent spectral hole burning and laser assisted nanoparticle preparation, the dephasing time T2 of surface plasmon excitation in silver nanoparticles was systematically investigated. A strong dependence of T2 on the plasmon energy is found which reflects the relevance of interband damping and makes necessary a precise control of the particle shape when measuring T2. The influence of the reduced dimension on the dephasing dynamics was observed as a decrease of T2 with shrinking particle size. In addition, for silver nanoparticles on quartz substrates, a considerable amount of chemical interface damping was observed. 相似文献
14.
Fluorescent silver nanoparticles via exploding wire technique 总被引:2,自引:0,他引:2
Aqueous solution containing spherical silver nanoparticles of 20–80 nm size have been generated using a newly developed novel
electro-exploding wire (EEW) technique where thin silver wires have been exploded in double distilled water. Structural properties
of the resulted nanoparticles have been studied by means of X-ray diffractometer (XRD) and transmission electron microscopy
(TEM). The absorption spectrum of the aqueous solution of silver nanoparticles showed the appearance of a broad surface plasmon
resonance (SPR) peak centered at a wavelength of 390 nm. The theoretically generated SPR peak seems to be in good agreement
with the experimental one. Strong green fluorescence emission was observed from the water-suspended silver nanoparticles excited
with light of wavelengths 340, 360 and 390 nm. The fluorescence of silver nanoparticles could be due to the excitation of
the surface plasmon coherent electronic motion with the small size effect and the surface effect considerations 相似文献
15.
R. R. Shamilov V. I. Nuzhdin V. F. Valeev Yu. G. Galyametdinov A. L. Stepanov 《Technical Physics》2016,61(11):1698-1703
Multilayer systems consisting of layers of hybrid quantum dots are fabricated. The quantum dots with the CdSe/CdS core/shell structure are chemically synthesized and deposited on the surface of quartz glass that contains ion-synthesized silver nanoparticles in the near-surface region. Silver nanoparticles exhibit optical absorption owing to the localized surface plasmon resonance. Variations in the photoluminescence intensity of the layer related to an increase in the distance from the quartz surface with metal nanoparticles are studied. An increase in the photoluminescence intensity is observed under excitation in the spectral region of the plasmon absorption of silver nanoparticles. An optimal distance between the layers is determined to maximize the enhancement of the photoluminescence of quantum dots in the presence of the near field of metal nanoparticles. 相似文献
16.
Strong coupling of molecular electronic states with tunable surface plasmon resonances is used to control electronic energy redistribution pathways in molecules adsorbed on a silver film. Ultrafast excitation of porphyrinic molecular J aggregates into the S2 state is followed by a second pulse of varying incident wave vector to produce a tunable plasmon in the film. When the plasmon overlaps the S1 state, energy flows from S2 to S1 at high efficiency. If the plasmon hybridizes with the S2 state, the excitation remains in the S2 vibrational manifold during quenching to the ground state. These results could have significant impact on the design of active molecular devices. 相似文献
17.
S. V. Vinogradov M. A. Kononov S. I. Valyanskii A. G. Makarov V. V. Savranskii 《Bulletin of the Lebedev Physics Institute》2012,39(1):12-15
The effect of the surface optical sensitization (SOS) of silver iodide in a multilayer structure by trace amounts of gaseous
molecules of brilliant green dye is demonstrated. Using the surface plasmon resonance excitation, it is shown that the SOS
causes changes in the surface layer parameters and can be used to develop highly sensitive and selective gas sensors. 相似文献
18.
Seal K Genov DA Sarychev AK Noh H Shalaev VM Ying ZC Zhang X Cao H 《Physical review letters》2006,97(20):206103
Near-field intensity statistics in semicontinuous silver films over a wide range of surface coverage are investigated using near-field scanning optical microscopy. The variance of intensity fluctuations and the high-order moments of intensity enhancement exhibit local minima at the percolation threshold. This reduction in local field fluctuations results from resonant excitation of delocalized surface plasmon modes. By probing the modification of the critical indices for high-order moments of intensity enhancement caused by the delocalized states, we provide the first experimental evidence for the coexistence of localized and delocalized surface plasmon modes in percolating metal films. 相似文献
19.
A novel theoretical approach to the dynamics analysis of excitation and dephasing of plasmon modes in nanoparticles is presented. This approach is based on the biorthogonal plasmon mode expansion, and it leads to the predictions of time dynamics of excitation of specific plasmon modes as well as their steady state amplitude and their decay. Temporal characteristics of plasmon modes in nanoparticles are expressed in terms of their shapes, permittivity dispersion relations, and excitation conditions. In the case of the Drude model, analytical expressions for time-dynamics of plasmon modes are obtained. 相似文献
20.
Yong‐Hyok Kwon Robert Ossig Frank Hubenthal Heinz‐Detlef Kronfeldt 《Journal of Raman spectroscopy : JRS》2012,43(10):1385-1391
We present experimental results to quantify and optimize the surface‐enhanced Raman scattering (SERS) activity of naturally grown silver nanoparticles. Ag nanoparticle ensembles with mean equivalent radii ranging from 10.6 to 20.3 nm were prepared under ultrahigh vacuum conditions by Volmer–Weber growth on quartz plates. A tuning of the localized surface plasmon polariton resonance wavelength from 453 to 548 nm was performed by varying the morphology of the silver nanoparticles. The dependence of the SERS activity on the plasmon resonance wavelength was investigated with a Raman set‐up containing a microsystem light source with an emission line at 488 nm. Shifted excitation Raman difference spectroscopy was applied to remove the fluorescence‐based background from the SERS spectra of pyrene in water using two slightly different emission wavelengths (487.61 and 487.91 nm) of the microsystem light source. We demonstrate that the Raman activities for all SERS substrates are available in the nanomolar range in a water sample. However, the Raman activity crucially depends on the plasmon resonance wavelength of the nanoparticle ensembles. Although for an on‐resonance ensemble the limit of detection for pyrene in water is very low and was estimated to be 2 nmol/L, it increases rapidly to several tens of nanomol for slightly off‐resonance ensembles. Hence, the highest SERS activity was obtained with a nanoparticle ensemble exhibiting a plasmon resonance wavelength at 491 nm, which almost coincides with the excitation wavelengths. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献