scholarly journals Theoretical Analysis of Plasmon Dispersion in Simple Metals

1979 ◽  
Vol 32 (4) ◽  
pp. 361 ◽  
Author(s):  
Peter Jewsbury
Keyword(s):  
Random Phase Approximation ◽  
Random Phase ◽  
Electron Gas ◽  
Incident Beam ◽  
Inelastic Electron ◽  
Plasmon Peak ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra ◽  
Plasmon Dispersion ◽  
Good Agreement

The dielectric response of an electron gas has been investigated with a view to understanding the small momentum behaviour of the plasmon peak in inelastic electron energy loss spectra. It is shown that the lifetime of the plasmon and the width of the incident beam both contribute to the apparent flattening of the plasmon dispersion which has been seen to occur in some metals (magnesium, aluminium, indium) for plasmon wavevectors less than ~O�5 A -1. Expressions, beyond the random phase approximation, are derived for the dispersion coefficients up to fourth order in the plasmon wavevector. Good agreement with experiment is obtained.

scholarly journals Electron-Energy-Loss Spectra of Free-Standing Silicene

2014 ◽  
Vol 28 ◽  
pp. 1-7 ◽  
Author(s):  
Luis M. Priede ◽  
Lilia Meza-Montes
Keyword(s):  
Random Phase Approximation ◽  
Random Phase ◽  
Tight Binding ◽  
Nearest Neighbors ◽  
Free Standing ◽  
Two Dimensional Materials ◽  
Space Discretization ◽  
Semi Empirical ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

Silicene is becoming one of the most important two-dimensional materials. In this work, EEL Spectra were calculated for α-silicene (flat), and β-silicene (low-buckled, and theoretically the most stable). Band structures were determined using the semi-empirical Tight-Binding Method considering second nearest neighbors, sp3 model, Harrison's rule, and Slater-Koster parameterization. The dielectric function was calculated within the Random Phase Approximation and a space discretization scheme. We found that, compared to bulk Si, additional resonances appear which are red-shifted. Buckling gives rise to a richer structure at low energy.

scholarly journals Ab-initio study of electronic and magneto-optical properties of InAs:Mn

2018 ◽  
Vol 185 ◽  
pp. 06008 ◽  
Author(s):  
Elena Gan’shina ◽  
Erkin Kulatov ◽  
Leonard Golik ◽  
Zoya Kun’kova ◽  
Yurii Uspenskii ◽  
...  
Keyword(s):  
Optical Properties ◽  
Ground State ◽  
Kerr Effect ◽  
Energy Difference ◽  
Dielectric Tensor ◽  
Ab Initio Study ◽  
State Distribution ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra ◽  
Good Agreement

Energy difference between the ferromagnetic and antiferromagnetic collinear orderings has been calculated for the uniform and dimer Mn-pair geometries in order to find the ground state distribution of the Mn atoms in InAs host. We find the preference of the dimer ferromagnetic configuration of Mn dopants and an importance of optimizing the atomic site positions. The frequency-dependent optical and magneto-optical properties, namely the dielectric tensor (on-and off-diagonal components), the electron energy loss spectra, and the transversal Kerr effect (TKE), are calculated. Calculated TKE resonance in In1-xMnxAs (x=0.0625) is found to be in good agreement with corresponding experimental magneto-optical spectra. The origin of the large TKE is discussed.

Analysis of Collective Resonances in Clusters: Metals and Carbon

1992 ◽  
Vol 272 ◽  
Author(s):  
Vitaly V. Kresin
Keyword(s):  
Random Phase Approximation ◽  
Sum Rules ◽  
Random Phase ◽  
Closed Shell ◽  
Dynamical Response ◽  
Many Body ◽  
Resonance Frequencies ◽  
Unified View ◽  
Small Clusters ◽  
Good Agreement

ABSTRACTDipole photoabsorption spectra of small clusters are analyzed. Two types of systems are considered: metal clusters and the carbon fullerenes. Both have been found to exhibit strong collective photoabsorption modes associated with the motion of delocalized electrons. We describe analytical results for the resonance frequencies in both spherical (closed-shell metallic, C60 ) and spheroidal (openshell metallic, C70) particles. The calculation is based on the techniques of many-body physics (random-phase approximation, sum rules), affords a unified view of the dynamical response of microscopic clusters, and leads to good agreement with experimental data.

Systematic inclusion of the effect of an arbitrary surface profile on the dispersion of surface plasmons

1981 ◽  
Vol 59 (4) ◽  
pp. 540-547 ◽  
Author(s):  
P. Summerside ◽  
B. V. Paranjape
Keyword(s):  
Surface Plasmon ◽  
Random Phase Approximation ◽  
Iterative Scheme ◽  
Random Phase ◽  
Surface Profile ◽  
Step Function ◽  
Surface Diffuseness ◽  
Classical Boltzmann Equation ◽  
Plasmon Dispersion ◽  
Effect Of Surface

The classical Boltzmann equation approach is developed to systematically include the effect of surface diffuseness in the random phase approximation (RPA) surface plasmon dispersion relation. This is achieved by the introduction of an arbitrary surface potential energy barrier into the distribution function. The resulting Fourier-transformed, linearized equation is solved by a perturbative-iterative scheme based on an expansion of the response function beyond the usual step-function form. The surface plasmon dispersion curves obtained lend support to the more recent experimental results which indicate an almost flat to slightly increasing small wavenumber behaviour. Noticeable dipping of the curves only occurs for broad surface regions, suggestive of surface contamination.

Electron Radiation Damage on thin Films of Phenylalanine

1973 ◽  
Vol 31 ◽  
pp. 484-485
Author(s):  
P. S. D. Lin
Keyword(s):  
Mass Loss ◽  
Incident Beam ◽  
Mean Free Path ◽  
Carbon Films ◽  
Specimen Thickness ◽  
Thin Carbon ◽  
Incident Beam Intensity ◽  
The Mean ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

Consecutive observation of the mass loss and change in electron energy loss spectra are being carried on In a simple field emission scanning mlcroscope. The specimens are prepared by slow sublimation onto thin carbon films on a copper grid.For mass loss measurement, unscattered electrons Nun are counted, W'lich Is related to Incident beam Intensity N0 by Nun = N0 exp(-(ai+ae)t), where tIs a specimen thickness, ae, ai the Inverse of the mean free path for elastic and Inelastic scattering, respectively. With 20 KeV and 12 mrad aperture angle, most of the elastically scattered electrons are stopped by the aperture. The Inelastically scattered electrons arefll tered by the spectrometer.

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