Showing papers on "Plasmon published in 1973"
TL;DR: The surface plasmon may be regarded as the source of the image force at an external charge and of dispersion forces between solids as mentioned in this paper, and some of the properties of surface plasmons in nearly free-electron solids are reviewed.
266 citations
TL;DR: In this article, an average dielectric function is defined for a layer of small interacting, absorbing spheres which has the Lorentz form for either phonon or plasmon excitations.
218 citations
TL;DR: In this paper, the dispersion of surface plasmons at an air-metal interface has been studied experimentally using the method of attenuated total reflection, and it was shown that surface plasmon interactions must be characterized by a complete response-function surface rather than by a single dispersion curve.
Abstract: The dispersion of surface plasmons at an air-metal interface has been studied experimentally using the method of attenuated total reflection. In the vicinity of the surface plasmon energy the dispersion curve was found to bend back toward the light line instead of increasing asymptotically to the surface plasmon energy at infinite momentum. We conclude that surface plasmon interactions must be characterized by a complete response-function surface rather than by a single dispersion curve.
125 citations
TL;DR: The theory of x-ray photoemission and related experiments involving the excitation of a core state interacting with plasmons is presented in this paper, where the effects of the solid surface have been calculated, thus complementing the authors' previous calculation of the bulk effects.
Abstract: The theory of x-ray photoemission (and related experiments) involving the excitation of a core state interacting with plasmons is presented. Specifically, the effects of the solid surface have been calculated, thus complementing the authors' previous calculation of the bulk effects. The strengths of the surface- and bulk-plasmon satellites associated with (i) the sudden appearance of the deep hole, (ii) the escape of the photoelectron, and (iii) interference between these have been calculated.
94 citations
TL;DR: In this paper, the peculiarities of the damped longitudinal plasma and lattice vibrations coupling in GaAs are analyzed with the help of a factorized dielectric function, based on the model of arbitrary bonded oscillators.
94 citations
TL;DR: In this paper, the authors made measurements to study how Cs and O adsorb onto the (100) surface of p-type degenerate Si to produce negative electron affinity (NEA).
80 citations
TL;DR: In this article, the authors studied the dynamical dielectric response of a condensed system of molecules with permanent electric dipole moments, and obtained a diversity of both collective and single particle behavior, consistently, over the entire range of frequencies below those of intramolecular excitation.
Abstract: The dynamical dielectric response of a condensed system of molecules with permanent electric dipole moments is studied. We start from the dynamical extension of the Onsager theory developed by Nee and Zwanzig, but generalized so as to be applicable at high frequencies. Specifically, we retain inertial terms and introduce relaxation effects in a way valid in a high frequency limit. The dielectric function obtained incorporates a diversity of both collective and single‐particle behavior, consistently, over the entire range of frequencies below those of intramolecular excitation. It is noteworthy that not only is a collective mode, or dipolar plasmon, exhibited, but that its frequency is also a resonance of the single‐dipole motion. The properties of the dielectric function are analyzed and illustrated in detail, and specific applications are made to water, to hydrogen chloride, and to chloroform.
73 citations
TL;DR: In this paper, a modified version of the Mitchell-Makinson time-dependent perturbative calculation of the surface photoelectric effect has been carried out based on a significantly improved treatment of surface-polarization charge-density variations.
Abstract: A modified form of the Mitchell---Makinson time-dependent perturbative calculation of the surface photoelectric effect has been carried out based on a significantly improved treatment of surface-polarization charge-density variations. The approach taken allows calculation of the excitation current back into the metal as well as into vacuum, and is generally applicable to the surface wave (plasmon) or to the direct optical mode of $p$-polarized-light excitation of the surface effect. Numerical results are presented for aluminum, but the general conclusions of the paper should be applicable to all nearly-free-electron metals. The behavior of the surface charge is shown to have a fundamental effect upon the frequency dependence of the surface effect, causing a marked enhancement in the effect at low energies followed by an almost total suppression of the surface effect at energies near the volume plasma energy. Surface photoexcitation at these lower energies is shown to dominate the photoemission from surface-wave decay as well as from direct optical excitation at high angles of light incidence. The surface-wave (plasmon) mode of excitation is shown to be particularly strong, with surface excitation dominating the decay of the high-$k$ plasmons typically excited on real surfaces. Comparisons of the results of this calculation are made with existing experimental data, and the prediction that surface waves (plasmons) should form a uniquely strong mode of surface-effect excitation is shown to be quantitatively consistent with recent experimental studies of photoemission in surface-plasmon decay. The historical failure to observe direct optical excitation of the surface photoelectric effect in the alkalis is explained, and a suggestion for detecting direct-optical excitation of the effect in other nearly-free-electron metals is made based on the results of this calculation.
67 citations
TL;DR: In this paper, X-ray scattering studies in single-crystal beryllium reveal an anisotropy in both the plasmon dispersion and linewidth, and by comparing the data with random-phase approximation-type theory which includes band structure, they can begin to separate the contributions from the lattice and from true many-body interactions to the temporally and spatially dependent response of an interacting electron gas at metallic densities.
Abstract: X-ray scattering studies in single-crystal beryllium reveal for the first time an anisotropy in both the plasmon dispersion and linewidth. By comparing the data with random-phase-approximation-type theory which includes band structure, we can begin to separate the contributions from the lattice and from the true many-body interactions to the temporally and spatially dependent response of an interacting electron gas at metallic densities.
66 citations
TL;DR: In this paper, the average energy to create an electron-hole pair, Ex, is given essentially by ℏ ωp/n, where ω p is the plasmon energy and n is the number of pairs which are created by the plasmons and its decay products.
Abstract: Fast electrons in solids lose energy primarily to plasmons which subsequently decay into an electron‐hole pair. The electron and hole may create additional electron‐hole pairs if they have sufficient energy. The average energy to create an electron‐hole pair, Ex, is thus given essentially by ℏ ωp/n, where ℏ ωp is the plasmon energy and n is the number of pairs which are created by the plasmon and its decay products. The values of n and hence Ex depend on the ratio ℏωp/Eg, where Eg is the usual band gap in semiconductors and insulators. We have found that for a simple model of direct and indirect materials, sharp thresholds exist for various values of n. For direct‐gap materials, n=1 for 1< ℏωp/Eg<4, n=3 for 4< ℏωp/Eg<12, etc. Similar relations for indirect‐gap materials have also been obtained. Consideration of phonon losses, effective masses, and problems with k conservation indicate that the changes in n vs ℏωp/Eg should be smoothed for real materials. but not eliminated. Our theoretical values for Ex/E...
61 citations
TL;DR: In this article, the authors compared the theoretical and experimental surface plasmon dispersion curve ω(k) of InSb obtained by using samples with line gratings in the surface and by using the technique of attenuated total reflection (ATR).
TL;DR: The APS spectra of Al, Mg, and Be have been measured and good correlations to soft X-ray absorption spectra and density of states calculations are found as discussed by the authors.
TL;DR: In this paper, the electron plasmon-emission-mean free path in semi-infinite Jellium is evaluated as a function of position, and of electron emergence angle.
TL;DR: In this paper, the size and shape dependence of the properties of long wave optical phonons in polar crystals is discussed, and the main effect occurring due to the presence of surfaces is the appearance of a surface optical phonon band in the frequency region between the frequencies ω t and ω l of the long wave transverse and longitudinal bulk modes.
TL;DR: In this paper, the surface excitations of phonon and plasmon character are reviewed and discussed using the electric field response function, and the surface mode dispersion curves are exhibited for InSb for carrier concentrations in the 1 to 6 × 1017 cm−3 range.
TL;DR: In this paper, the optical conductivity of K2Pt (CN)4Br0,3 · 3H2O single crystals for phonon energies near the plasma edge is investigated.
ESRO1
TL;DR: In this paper, the authors derived the long-range electron-Coulomb correlation to the surface energy of an empty spherical cavity in a metal from the zero-point energy of surface plasmons characteristic of the spherical void boundary.
Abstract: The contribution of the long-range electron-Coulomb correlation to the surface energy of an empty spherical cavity in a metal is calculated from the zero-point energy of surface plasmons characteristic of the spherical void boundary. At large void radii one recovers the result previously derived for a planar metal-vacuum interface. Next it is shown that, owing to the overlapping of surface-plasmon zero-point oscillations around two neighboring voids, an effective attraction exists between them which is analogous to the van der Waals (dispersion) forces between small metal spheres in vacuum. However, because of the monopole nature of the fundamental surface-plasmon mode of a void, the effective void-void interaction is much stronger and of much longer range than the attraction of spherical particles for which the lowest-order plasmon mode is of dipole type only. It is therefore proposed that plasmons may be one of the important physical processes responsible for void nucleation and growth and also for the observed occurrence of three-dimensional void arrays in some heavily irradiated transition metals. In a void lattice, the plasmon modes of an isolated void split and broaden into bands. The resulting plasmon cohesive energy per void is estimated to be of the order of -1 eV for the observed bcc void array in molybdenum and -2.5 eV for the fcc nickel array.
TL;DR: In this article, the authors showed that there is no increase of the frequency of the surface plasma oscillation with increasing wave vector, which is not in agreement with theory, and they used energy loss experiments with 50 keV electrons on thin films of Al and Mg.
TL;DR: In this article, the dispersion of surface-plasma oscillations is calculated analytically, using the Bloch hydrodynamic model for an electron gas and solving Maxwell's equations in the absence of retardation effects.
Abstract: The dispersion of surface-plasma oscillations is calculated analytically, using the Bloch hydrodynamic model for an electron gas and solving Maxwell's equations in the absence of retardation effects. This study is based on an approximation for a constitutive relation which provides a useful alternative to previous model descriptions of the surface. It is found that at long wavelengths the surface-plasmon dispersion relation includes a term which is linear in the momentum parallel to the surface and which is half as large as in the case of a study for specular reflection. In contrast to hydrodynamic treatments for specular reflection, the present one leads to an appreciable Landau damping of the surface-plasma oscillations. The magnitude of this Landau damping is roughly consistent with the results of a recent numerical study of plasmons for a more realistic model of the surface. Also discussed in some detail are the charge-density fluctuations associated with the surface plasmon, and a useful relation is established between the amplitudes of bulk- and surface-charge oscillations. In an appendix it is shown that when the imaginary part of the hydrodynamic dielectric function is neglected, one is led to surface modes which are quite different from the usual surface plasmon. Finally the results for surface plasmons are compared with those which are obtained for surface phonons in a metal film and the relationship between two different recent analyses of the surface-phonon problem is discussed in some detail.
TL;DR: In this article, the authors investigated the relationship between the CK core hole excitation and strong plasmon emission in the soft X-ray appearance potential spectroscopy (APS) technique.
Abstract: The technique of soft X-ray appearance potential spectroscopy (APS) has been applied to pyrolytic graphite and other carbons. The prominent, sharp satellites in the spectrum are assigned, in agreement with Houston and Park, to a coupling of the CK core hole excitation to strong plasmon emission (first and higher orders of the 7 eV plasmon and first order of the 27 eV plasmon). However, the peak separations of the higher order 7 eV plasmons are found to be not constant. The broad loss peaks are assigned to coupling with interband transitions. Increasing the degree of disorder of the carbon markedly affects the spectrum. The results are discussed in the light of more direct experimental investigations of electronic excitations in graphite, and of recent theoretical considerations of plasmon coupling in APS.
Die Technik der Schwellenenergie-Spektroskopie (APS) weicher Rontgenstrahlung wurde auf Pyrographit und andere Kohlenstoffarten angewandt. In Ubereinstimmung mit, Houston und Park werden die gefundenen intensiven, schmalen Satelliten im Spektrum auf starke Kopplung der „core hole”-Anregang mit Plasmonenemission (erste und hohere Ordnungen des 7 eV-Plasmons und erste Ordnung des 27 eV-Plasnions) zuruckgefuhrt. Die Abstande zwischen den hoheren Ordnungen des 7 eV-Plasmons sind jedoch nicht konstant. Die breiten Verluste werden durch Kopplung mit Interbandubergangen erkart. Eine Erhohung der Unordnung im Kohlenstoff verandert das Spektrum deutlich. Die Ergebnisse werden im Hinblick aiif die direkten experimentellen Untersuchungen von elektronischen Anregungen in Graphit und auf die jungsten theoretischen uberlegungen zur Plasmonenkopplung bei APS diskutiert.
TL;DR: In this paper, electron energy loss spectroscopy was applied to a K layer adsorbed on Ni(100) and the observed excitation energy depends on the density of K atoms in the layer.
TL;DR: In this article, the charge density fluctuation in a surface plasmon is calculated for a step-potential model of an Al surface and the dispersion relation is found for low K. At low K the plasman is largely localized to within an atomic radius of the surface, but at high K no localized mode is found.
Abstract: The charge density fluctuation in a surface plasmon is calculated for a step-potential model of an Al surface. At low K the plasmon is largely localized to within an atomic radius of the surface, but at high K no localized mode is found. The dispersion relation is found for low K.
TL;DR: The agreement between a recently propounded theory of metallic surface energies and experiment is a consequence of the arbitrary choice of the same plasmon cut-off wavevector, k c, for both bulk and surface plasmons as discussed by the authors.
TL;DR: In this article, the properties of acoustic plasmon excitations and the conditions for their existence in a metal with two overlapping bands one of which is narrow and the other broad are discussed.
TL;DR: In this article, the local surface plasmon dispersion relation for a slab of plasma in a magnetic field (perpendicular to the slab faces) was analyzed, and the magnetic field modifications of both antisymmetric and symmetric slab surfaces modes were determined in the local limit.