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1.
M. Quinten 《Applied physics. B, Lasers and optics》2001,73(4):317-326
We discuss the dependence of the color of low-concentrated nanoparticle systems on particle size and mass concentration for
Ag, Au and TiN nanoparticles, which exhibit a surface plasmon polariton resonance in extinction spectra. Comparison is made
with color data obtained for Ag and Au colloidal suspensions.
When particles lump into aggregates, the splitting of the surface plasmon resonance into new resonances affects the extinction
of light and, hence, the color of the particle assembly. This is demonstrated for aggregated colloidal suspensions of Ag and
Au nanoparticles.
Finally, for highly concentrated assemblies such as pigment films, we discuss the dependence of the color in diffuse reflectance
and transmittance according to Kubelka and Munk (P. Kubelka, F. Munk: Z. Techn. Phys. 12, 593 (1931)), and extend this model by using optical properties of aggregates of spheres.
Received: 2 July 2001 / Published online: 10 October 2001 相似文献
2.
We present extinction measurements on rectangular two-dimensional arrays of gold nanoparticles on a dielectric waveguide.
The spectra exhibit spectrally narrow bands of suppressed extinction within the particle–plasmon resonance, resulting from
destructive interference between the incident light field and the excited waveguide modes. The dependence of the spectral
position of these high-transmission bands on different waveguide modes is investigated in detail.
Received: 3 July 2001 / Published online: 10 October 2001 相似文献
3.
The effect of the temperature of a silver sol on its extinction spectra during formation of aggregates of plasmon resonance nanoparticles with varying degree of order and the effect exerted on these spectra by changes in the structure of a colloidal crystal during its heating, which lowers elastic properties of a polymer adsorption layer of particles are studied. 相似文献
4.
The effect of the temperature of a silver sol on its extinction spectra during formation of aggregates of plasmon resonance
nanoparticles with varying degree of order and the effect exerted on these spectra by changes in the structure of a colloidal
crystal during its heating, which lowers elastic properties of a polymer adsorption layer of particles are studied. 相似文献
5.
R. A. Ganeev G. S. Boltaev R. I. Tugushev T. Usmanov 《Applied Physics A: Materials Science & Processing》2010,100(1):119-123
We demonstrate that the nanoparticle formation during laser ablation of metals by short (of a few tens of ps) laser pulses
strongly depends on the concentration of surrounding gas. While, at vacuum conditions, nanoparticle formation shows very “sharp”
atomic force microscope images of aggregated clusters, following with clear appearance of plasmon resonance on the absorption
spectra of deposited films, an addition of gas particles starts to decrease the probability of cluster formation. This process
shows a threshold for both helium (33 torr) and xenon (12 torr) above which no surface plasmon resonance and correspondingly
no observable nanoparticles on the deposited surfaces were detected. The destruction of nanoparticle formation was attributed
to the negative influence of surrounding gas particles on ablated particles aggregation. 相似文献
6.
C. Kennerknecht H. Hövel M. Merschdorf S. Voll W. Pfeiffer 《Applied physics. B, Lasers and optics》2001,73(4):425-429
The resonant multiple excitation of collective modes in metallic nanoparticles using ultrashort laser pulses leads to an enhanced
multiphoton photoemission from the particles. This effect is here demonstrated for the surface-plasmon resonance of Au nanoparticles
on graphite. The shape of the photoemission spectra is explained by multiphoton photo-assisted thermionic emission from the
nanoparticles and resonant emission via the image-potential state on graphite. Tuning the photon energy between 1.7 eV and
3.2 eV allows the identification of an enhancement of the photoemission yield at 2.1±0.1-eV photon energy that is attributed
to the resonant excitation of the surface plasmon in the Au nanoparticles. This identification of the surface-plasmon excitation
in this energy range is also supported by electron energy loss spectroscopy.
Received: 8 August 2001 / Revised version: 13 September 2001 / Published online: 10 October 2001 相似文献
7.
S.R. Sershen S.L. Westcott J.L. West N.J. Halas 《Applied physics. B, Lasers and optics》2001,73(4):379-381
Metal nanoshells, which are nanoparticles consisting of a dielectric core surrounded by a metal shell, have an optical response
dictated by the plasmon resonance. This optical resonance leads to large extinction cross-sections, which are typically several
times the physical cross-section of the particles. The wavelength at which the resonance occurs depends on the core and shell
sizes, allowing nanoshells to be tailored for applications. In this paper, we demonstrate how incorporating nanoshells transforms
a thermoresponsivepolymer into a photothermally responsive nanoshell–polymer composite. When the thermoresponsive polymer,
co-N-isopropylacrylamide-acrylamide (NIPAAm-co-AAm), is heated, the polymer undergoes a reversible decrease in volume. Pristine
NIPAAm-co-AAm does not inherently absorb visible or near infrared light. However, by incorporating metal nanoshell particles
with a resonance that has been placed at 832 nm into the NIPAAm-co-Aam, nanoshell–polymer composite hydrogels are fabricated.
When the composite is illuminated with a diode laser at 832 nm, the nanoshells absorb light and convert it to heat. This induces
a reversible and repeatable light-driven collapse of the composite with a weight change of 90% after illumination at 1.8 Wcm-2.
Received: 18 July 2001 / Published online: 10 October 2001 相似文献
8.
Depth profiles of Ag nanoparticles in silicate glass 总被引:1,自引:0,他引:1
Xiuchun Yang Weijie Li Zhihui Li Yanan Wei Wenhai Huang 《Applied Physics A: Materials Science & Processing》2008,90(3):465-467
Silver nanoparticle composite glass has been synthesized by ion exchange and a subsequent thermal treatment method. Transmission
electron microscopy (TEM) and ultraviolet-visible spectrometry were used to study the depth profiles of Ag nanoparticles in
silicate glass. Results indicate that Ag nanoparticles are nearly spherical in shape with a single-crystalline structure.
Also, the volume fraction of Ag nanoparticles is very high in the surface layer of 5 μm, and then decreases slowly across
the depth of 30 μm, thereafter the volume fraction reduces quickly to zero at the depth of 100 μm. The plasmon resonance bi-absorptions
in the surface layer of the annealed specimen at 600 °C can be attributed to bi-modal distributions of Ag nanoparticles in
the layer. The bi-modal distributions can be explained by the Ostwald ripening theory.
PACS 81.05.Pj; 81.07.-b; 68.37.Lp 相似文献
9.
Controlled plasmon coupling is observed in nanoparticle assemblies composed of 20 nm silver ‘satellite’ nanoparticles tethered
by reconfigurable duplex DNA linkers to a 50 nm gold ‘core’ particle. The assemblies incorporate silver nanoparticle–oligonucleotide
conjugates prepared using a new conjugation method in which the recognition strand is anchored by a 10 base pair, double strand
spacer that presents adjacent 3’- and 5’-thiols to the silver surface. Reconfiguration of the DNA linkers from a compact to
an extended state results in decreased core–satellite coupling and a blue-shift in the gold core plasmon resonance. The structural
basis for the observed resonance modulation is investigated through simulation of the scattering spectra of binary assemblies
with various core–satellite separations. Additional simulations of core–satellite assemblies composed of gold satellite particles
bound to silver cores and of assemblies composed entirely of silver particles are used to clarify the dependence of the coupling
response on the composition of the components and their distribution within the assembly.
Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users. 相似文献
10.
Santanu Pyne Priyanka Sarkar Samita Basu Gobinda Prasad Sahoo Dipak Kumar Bhui Harekrishna Bar Ajay Misra 《Journal of nanoparticle research》2011,13(4):1759-1767
Synthesis of core @ shell (Au @ Ag) nanoparticle with varying silver composition has been carried out in aqueous poly vinyl
alcohol (PVA) matrix. Core gold nanoparticle (~15 nm) has been synthesized through seed-mediated growth process. Synthesis
of silver shell with increasing thickness (~1–5 nm) has been done by reducing Ag+ over the gold sol in the presence of mild reducing ascorbic acid. Characterization of Au @ Ag nanoparticles has been done
by UV–Vis, High resolution transmission electron microscope (HRTEM) and energy dispersive X-ray (EDX) spectroscopic study.
The blue shift of surface plasmon resonance (SPR) band with increasing mole fraction of silver has been interpreted due to
dampening of core, i.e. Au SPR by Ag. The dependence of nonlinear optical response of spherical core @ shell nanoparticles
has been investigated as a function of relative composition of each metal. Simulation of SPR extinction spectra based on quasi-static
theory is done. A comparison of our experimental and the simulated extinction spectra using quasi-static theory of nanoshell
suggests that our synthesized bimetallic particles have core @ shell structure rather than bimetallic alloy particles. 相似文献
11.
M. Quinten 《Applied physics. B, Lasers and optics》2001,73(3):245-255
A refined discussion of the near-field scattering of spherical nanoparticles and the electromagnetic fields close to the particle
surface is given. New results for the dependence on the distance from the surface and the angular distribution of the scattered
light in the near-field are given. It will be shown that the radial component of the electric field leads to striking differences
in the phase functions in the near-field and the far-field. Exemplary computations are presented for Ag and Au particles with
different size. In a second part the discussion is extended to assemblies of spherical Ag and Au nanoparticles. It will be
shown that large near-fields at wavelengths commonly used in SERS experiments are obtained for aggregates. In the near-field
scattering intensity “hot spots” mark regions between particles in the aggregate where the near-field is particularly high.
Received: 4 May 2001 / Revised version: 20 July 2001 / Published online: 19 September 2001 相似文献
12.
K. Kolwas A. Derkachova M. Shopa 《Journal of Quantitative Spectroscopy & Radiative Transfer》2009,110(14-16):1490-1501
The change of the scattering properties of sodium, gold and silver spherical particles with size is discussed in the context of surface multipolar plasmon resonances. The presented surface plasmon size characteristics are abstracted from the quantity which is observed and deliver multipolar plasmon resonance frequencies and plasmon damping rates in the form of a continuous function of particle radius. The performed analysis of the plasmon dispersion relation is analogous to the problem of surface plasmon localized at a semi-infinite, flat metal/dielectric interface.Correlation between the multipolar plasmon resonance parameters, and the spectroscopic optical properties of conductive nanoparticles appearing as peaks in the measurable light intensities is analyzed. We discuss the fact, that such peaks arise from interference of all the electromagnetic fields contributing to the measured intensity, and not solely to the fields due to surface plasmon multipolar modes.We describe the results of light scattering experiment in orthogonal polarization geometries with use of spontaneously growing sodium droplets. The polarization geometry of the experiment allows for distinct separation of resonant contribution of dipole and quadrupole plasmon TM mode contributions to the measured intensities as a function of size.Predictions concerning size characteristics for dipole and quadrupole plasmons are compared with the results of light scattering experiments using spherical sodium droplets (our results) and gold and silver particles in suspension [other authors: Sönnichsen C, Franzl T, Wilk T, von Plessen G, Feldmann J. Plasmon resonances in large noble-metal clusters. New J Phys 2002; 4:93.1–8; Haiss W, Thanh NTK, Aveyard J, Fernig DG. Determination of size and concentration of gold nanoparticles from UV–vis spectra. Anal Chem 2007; 79:4215–21; Njoki PN, Lim I-IS, Mott D, Park H-Y, Khan B, Mishra S, et al. Size correlation of optical and spectroscopic properties for gold nanoparticles. J Phys Chem C 2007; 111:14664–9; Mock JJ, Barbic M, Smith DR, Schultz DA, Schultz S. Shape effects in plasmon resonance of individual colloidal silver nanoparticles. J Chem Phys 2002; 116:6755–9]. 相似文献
13.
We present comparative measurements of two Mach–Zehnder interferometers, one with Y-junction couplers and the other with MMI couplers, both developed in silicon-on-insulator technology and using plasma dispersion
effect for light phase modulation. Measurements of fiber-to-fiber losses, absorption coefficient, output intensity vs. time
and extinction ratio vs. frequency have been performed at λ=1.3 μm and at λ=1.55 μm. Results are reported and discussed in
this paper.
Received: 18 May 2001 / Revised version: 24 September2001 / Published online: 30 October 2001 相似文献
14.
H. Uchida Y. Masuda R. Fujikawa A.V. Baryshev M. Inoue 《Journal of magnetism and magnetic materials》2009,321(7):843-845
A large enhancement of the Faraday rotation, which is associated with localized surface plasmon resonance (LSPR), was obtained in a sample with Au nanoparticles embedded in a Bi-substituted yttrium iron garnet (Bi:YIG) film. On a quartz substrate, Au nanoparticles were formed by heating an Au thin film, and a Bi:YIG film was then deposited on them. A sample containing the Au nanoparticles produced by 1000 °C heating showed a resonant attenuation with narrower bandwidth in the transmission spectrum than nanoparticles of other samples formed by low-temperature heating. The sharp resonant Faraday rotation angle was 4.4 times larger than the estimated intrinsic Bi:YIG film at the LSPR wavelength; the angular difference was 0.14°. A discrepancy in the bandwidth between the transmission attenuation and the resonant Faraday rotation is discussed. 相似文献
15.
Gold nanoparticles with silver nanoshells are obtained by synthesizing gold nanorods in a growing solution containing cetyltrimethylammonium
bromide, subsequent separation in a concentration gradient of glycerol, and reduction of silver nitrate by ascorbic acid under
alkaline conditions in the presence of polyvinylpyrrolidone. The formation of silver nanoshells was monitored by the shift
of plasmon resonances of extinction and differential light scattering, by the appearance of characteristics peaks of silver
in the energy dispersive X-ray (EDX) spectra of samples, by the data of transmission electron microscopy, and by visual changes
in the color of colloids. The spectrum of the intensity ratio of the co- and cross-polarized compo- nents of light scattered
by gold-silver nanorods is measured for the first time, and it is observed that the maximum is shifted by 80–100 nm compared
to previously published spectra of gold nanorods (Khlebtsov et al., J. Phys. Chem. C 112, 12760 (2008)). The extinction and light scattering spectra are calculated by the method of separation of variables using
the model of a confocal two-layer spheroid and these calculations are found to agree with spectral measurements. A method
for determining the thickness of a silver nanolayer by the spectral shift of an extinction longitudinal resonance is described.
The obtained data of optical spectroscopy and transmission electron microscopy and estimations of the mass of the deposited
metal show that the aver-age thickness of the silver layer varies from 0.12 to 4 nm as the Ag/Au ratio changes from 2/80 to
90/80 μg/μg. 相似文献
16.
The excitation profile of the 1014 cm?1 Raman band of pyridine adsorbed on colloidal gold particles, and the extinction and elastic scattering spectra of the colloids, are measured as the colloids slowly aggregate in the presence of pyridine. Transmission electron microscopy shows that the aggregates formed are predominantly strings of particles rather than compact clusters, and the dipolar plasma modes of the aggregates are therefore split into longitudinal and transverse components. It is shown that only for excitation under the longitudinal resonance extinction band is there a large Raman intensity enhancement. The Raman excitation profile maximum corresponding to excitation under this resonance moves progressively to longer wavelengths, increasing substantially in height, as the aggregation proceeds. Thus aggregation is most advantageous for the realization of large Raman signals from these colloids, the Raman intensity at a given excitation wavelength increasing approximately as the square of the absorbance at that wavelength as the aggregation proceeds. These observations are discussed in relation to the electromagnetic field enhancement contribution to the surface Raman effect, with which they are in general agreement, and the large increase in ¦?¦2 for gold and silver with increase in wavelength is shown to be a significant factor in accounting for some of these effects of aggregation. 相似文献
17.
F. Castillo E. De la Rosa E. Pérez 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,63(2):301-306
In this work, we report the fabrication and characterization of size controllable gold
nanoparticles (NPs) aggregates for their application in surface enhanced Raman scattering
(SERS). Aggregates were prepared using two methodologies: (i) by using silica particles
arrays as a template to agglomerate gold NPs between the inter-particle interstices, and
(ii) by functionalizing silica particles to be used as support to graft gold nanoparticles
and thus to form decorated silica particle arrays. These substrates were used in the
detection of Rhodamine 6G producing an enhancement factor (EF) from 104 to
106 that is associated to the increment of hot spot (HS) sites, and the fact
that plasmon resonance from aggregates and absorption wavelength of test molecules are
closely in resonance with excitation wavelength. The EF was also reduced when the plasmon
resonance was red-shifted as a result of the increment of aggregate size. In spite of
this, the EF is high enough to make these SERS substrates excellent candidates for sensing
applications. 相似文献
18.
采用离散偶极子近似方法计算了内嵌圆饼空心方形银纳米结构的消光光谱以及其近场的电场强度分布,并进一步与空心方形纳米结构的消光光谱和表面电场做比较.结果表明,在耦合作用下内嵌圆饼空心方形银纳米结构不仅产生了新的共振模式,而且新的共振模式在传统表面增强拉曼散射的激发波长范围内,进而可以弥补由于实验上运用纳米切片法所制备的空心方形纳米结构尺寸较大导致其共振吸收峰在远红外波长范围的不足.此外,可以通过改变内嵌圆饼空心方形银纳米结构的形貌参数调节其表面等离子体共振峰的共振波长,以满足在表面增强拉曼散射、生物分子或化学分子探测上的应用. 相似文献
19.
20.
The collective plasmon resonances in a monolayer formed by metal or metal-dielectric nanoparticles with dipole or quadrupole single-particle resonances are theoretically and experimentally studied. The extinction, scattering, and absorption spectra are calculated using an exact many-particle solution for the system of interacting particles. With increasing surface density of particles in the monolayer, the dipole resonance is suppressed, and the spectrum of the collective system is determined by the quadrupole plasmon only. It is shown that the selective suppression of the long-wavelength extinction band is caused by the collective suppression of the dipole scattering mode, whereas the short-wavelength absorption spectrum of the monolayer differs little from the single-particle spectrum. Using dark-field light and atomic force microscopy, the kinetics of self-assembling of nanoshells is studied. It is shown that the universal linear relation between the relative shift of the wavelength of the collective quadrupole resonance and the relative increment of the refractive index of the surrounding medium is implemented. 相似文献