Size dependences of the polarizability of the metal particles

Size dependences of the eigenfrequencies, quality factors and polarizabilities of small metallic particles-resonant radiating elements were examined. Limits of electrodynamic scaling regions and ones of plasmon oscillations predominance were established for two types of particles-spling-ring and core-shell resonators.     

Diamagnetism in small metal particles

We investigate the diamagnetic response of small metal particles using a quadratic confinement potential. We find that the dependence of the susceptibility on the magnetic field is rather sensitive to the symmetry of the applied confinement, while the dependence on the system size is similar to that of the bulk limit.     

On the size dependence of the optical absorption due to small metal particles

The quantum mechanical theory of Kawbata and Kubo is used to calculate the position of the Mie optical absorption peak for small silver particles. The calculated position is close to that obtained with a classical model and does not explain the shift to long wavelength experimentally observed.     

On the polarizability dyadics of electrically small, convex objects

This communication on the polarizability dyadics of electrically small objects of convex shapes has been prompted by a recent paper published by Sihvola and Lindell on the polarizability dyadic of an electrically gyrotropic sphere. A mini-review of recent work on polarizability dyadics is appended.     

Shell effects in small metal particles

By assuming periodic discrete electronic spectra, the properties of small metal particles are analyzed. The canonical partition function is obtained exactly. The heat capacity and the electronic magnetic susceptibility are calculated in the presence of a static magnetic field. These results are an extension of the calculations for an equally spaced spectrum. Preliminary considerations of the statistical theory of spectra are included.     

Microwave absorption by small metal particles

The dielectric response of small indium and iron crystals in complementary particle topologies is characterized by microwave absorption. A transition from non-absorptive to conducting behaviour was discovered in condensed indium-oil dispersions during thermal particle coarsening. Microwave losses in low-density networks of iron “nanocrystals” (sizes ≲ 10 nm) are attributed to percolation.     

Surface plasmons in small metal particles

The dielectric response of a small metal particle to a perturbing potentialv _L =r ^L Y _LM e ^iωt is considered within the random phase approximation (RPA). The static dielectric polarizability is found and the size dependence of the surface plasmon frequencies are then determined from sum rule calculations. When the particle radiusa is large compared to the Thomas-Fermi screening lengthr ₀ the RPA equation is transformed into a form appropriate for an analytical solution. The dynamic electric polarizability, the position and the width of the surface plasma resonance are found in the limita/r ₀?1.     

Thermal expansion in small metal clusters and its impact on the electric polarizability

The thermal expansion coefficients of Na(N) clusters with 8相似文献   

Surface plasmons in small layer metal particles

Positions of two surface plasma resonances in a layer metal particle containing a dielectric foreign nucleus are calculated within the random phase approximation. The results obtained give a possible explanation of a recent experimental observation by Genzel et al.¹ of two peak structure in the photoabsorption cross-section of small silver particles.     

Alkali atom chemisorption on small metal particles

A quantum mechanical model of ionic chemisorption on small metal particles is presented. The model takes into account the size dependence of the metal electronic properties and treats ionic and covalent bond contributions in a selfconsistent fashion. The binding energy and the charge at the adatom are found to be strongly size dependent.     

Optical properties of aggregates of small metal particles

Many-particle systems exhibit unique optical properties which strongly depend on the arrangement of the individual particles in the sample. Novel methods were applied to produce gold particle samples with their arrangements systematically varying from statistical disorder to densely packed particle aggregates of various mean sizes and shapes. Their optical extinction spectra vary from narrow bands in the VIS to broad multiple band structures extending into the IR, the peak structure proving to be more pronounced if the particles are larger. Numerical calculations of explicit extinction spectra were performed on corresponding prototypic particle aggregates taking both interior and exterior retardation effects into account. In special, for aggregates of 2 to 5 particles, respectively, definite attachments of measured extinction peaks to special aggregate types were achieved from these calculations and confirmed by TEM micrographs of the investigated samples.     

On the radiation from small particles

The laws of equilibrium radiation within cavities and from surfaces of bodies must be recast when the cavity or body dimension is of the same order as the wavelength being considered. New formulae for the Planck function, the Wien displacement law, and the Stefan-Boltzmann law for small spherical particles are presented in this paper in terms of the three independent variables temperature, wavelength, and diameter. The most significant element of the formulation for black particles is that radiant emission, or absorption, is not permitted at wavelengths greater than √2π times the particle diameter.     

Life-time of surface plasmons in small metal particles

Existing theories concerning the life-time of surface plasmons in small metal particles fail to explain recent experimental data for silver. Therefore, two of these theories were critically re-examined, and some numerical errors were found. The semi-classical approach by Lozovik et al. yields, after correction, physically reasonable results, which are nearly identical with theoretical results by Kreibig. The corrected RPA-result by Lushnikov et al. is in quantitative agreement with recent experimental data for silver.     

Size dependent ac conductivity of small metal particles

The statistical model of electrons in a small metallic particle is applied to calculate three expressions for the size dependent ac conductivity. The first expression is very simple. It is obtained with a sum-rule conserving ansatz for the electric dipole matrix element. The two other forms follow from generalizations of a quasiclassical approximation for the matrix element due to Gor'kov and Eliashberg. The results are discussed and related to other work.Dedicated to Professor W. Brenig on the occasion of his 60th birthday     

High precision measurement of the static dipole polarizability of cesium

The cesium 6(2)S(1/2) scalar dipole polarizability alpha(0) has been determined from the time-of-flight of laser cooled and launched cesium atoms traveling through an electric field. We find alpha(0)=6.611+/-0.009 x 10(-39) C m(2)/V=59.42+/-0.08 x 10(-24) cm(3)=401.0+/-0.6a(3)(0). The 0.14% uncertainty is a factor of 14 improvement over the previous measurement. Values for the 6(2)P(1/2) and 6(2)P(3/2) lifetimes and the 6(2)S(1/2) cesium-cesium dispersion coefficient C6 are determined from alpha(0) using the procedure of Derevianko and Porsev [Phys. Rev. A 65, 053403 (2002)]].     

Sum-rule studies for electrons in small metal particles

The electric dipole-matrix element of electrons in a small metallic grain is considered using sum rules and scaling concepts. Applying level statistical arguments a universal scaling form for the dipole-matrix element is obtained which reproduces the previously calculated frequency dependences in the ballistic, diffusive and localization regimes.     

Non-local conductivity and the effective potential in small metal particles

We discuss the absorption of electromagnetic radiation in small conducting particles, in the case where the electron motion is diffusive. We refine an earlier theory in which we calculated the absorption coefficient using an effective potential describing the screened electric field. Our new theory incorporates the effects of non-locality in the electrical conductivity, and shows how the two limiting behaviours of the effective potential at high and low frequencies can be derived from a unified theory. Our results are in full agreement with our earlier calculation. Received: 3 November 1997 / Accepted: 29 January 1998     

Dielectric function and infrared absorption of small metal particles

Using known quantum mechanical models of electrons in a box, a smoothed dielectric function is derived for an envelope taken over the discrete dipole transitions of a small metal particle. This dielectric function deviates strongly from the Drude function at low frequencies (IR) while it merges into the latter at high frequencies (visible and UV). The function is used then to show that it is not the electric but the magnetic dipole absorption due to eddy currents, contained already in the Mie scattering theory, which reproduces the small particle dielectric function in the infrared. The possibilities and limitations of experimental confirmation are discussed.     

Voids in icosahedral small particles of an electrolytic metal

Results of an experiment aimed at the detection of voids in small icosahedral particles of electrolytic copper are presented. The chosen experimental technique is theoretically justified. The presence of voids revealed in the experiment gives strong evidence that the formation of small particles and microcrystals with pentagonal symmetry is governed by the disclination mechanism.     

Red shift of surface plasmons in small metal particles

It is shown that the experimentally found red shift of the surface plasmon resonance in a small metal particle is a direct measure of the first moment of the induced surface charge.