Quantification of surface effects: Monte Carlo simulation of REELS spectra to obtain surface excitation parameter

K. Salma, Z. J. Ding, Z. M. Zhang, P. Zhang, K. Tőkési, D. Varga, J. Toth

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

The surface excitation effect is investigated by using the quantum mechanical frame work of complex self-energy of electrons which interact with a bounded semi-infinite medium. In the self-energy formalism, differential inverse inelastic mean free path (DIIMFP) has contributions from bulk and surface plasmons. Monte Carlo simulation of the interaction of electrons with a solid medium and surface has been performed. The surface excitation parameter (SEP) is then obtained from the simulated reflection electron energy loss spectroscopy (REELS) spectra. The calculated SEP results by Monte Carlo simulation are compared with the previous calculations of total surface excitation probability, which was estimated by a numerical integration of surface term of DIIMFP. The contribution merely due to surface excitations towards REELS spectra is extracted by subtracting the two Monte Carlo simulated REELS spectra that based on the two models of electron inelastic scattering, i.e. a full surface model (SM) and a pure bulk model (BM). The surface excitations found to be significant at low energy losses and diminish at higher energy losses whereas the bulk plasmon contributions show opposite behavior and are negligible at lower energy losses. The average number of surface excitations is then evaluated by the computation of ratio of the integrated surface contribution to the elastic peak. The calculated results for Ag are found to be reasonably in agreement with our previous results for total probability of surface excitations and other reported experimental data for SEP. Surface correction factor (SCF) is calculated using SEP for several metals and is compared with the reported ratio of SCF with Ni sample as reference.

Original languageEnglish
Pages (from-to)1236-1243
Number of pages8
JournalSurface Science
Volume603
Issue number9
DOIs
Publication statusPublished - May 1 2009

Fingerprint

Electron energy loss spectroscopy
energy dissipation
electron energy
spectroscopy
excitation
simulation
Energy dissipation
Monte Carlo simulation
mean free path
Inelastic scattering
Plasmons
Electron scattering
Electrons
numerical integration
plasmons

Keywords

  • Electron solid interactions
  • IMFP
  • Monte Carlo
  • REELS
  • Surface excitation parameter
  • Surface plasmon

ASJC Scopus subject areas

  • Surfaces and Interfaces
  • Condensed Matter Physics
  • Materials Chemistry
  • Surfaces, Coatings and Films

Cite this

Quantification of surface effects : Monte Carlo simulation of REELS spectra to obtain surface excitation parameter. / Salma, K.; Ding, Z. J.; Zhang, Z. M.; Zhang, P.; Tőkési, K.; Varga, D.; Toth, J.

In: Surface Science, Vol. 603, No. 9, 01.05.2009, p. 1236-1243.

Research output: Contribution to journalArticle

Salma, K. ; Ding, Z. J. ; Zhang, Z. M. ; Zhang, P. ; Tőkési, K. ; Varga, D. ; Toth, J. / Quantification of surface effects : Monte Carlo simulation of REELS spectra to obtain surface excitation parameter. In: Surface Science. 2009 ; Vol. 603, No. 9. pp. 1236-1243.
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AB - The surface excitation effect is investigated by using the quantum mechanical frame work of complex self-energy of electrons which interact with a bounded semi-infinite medium. In the self-energy formalism, differential inverse inelastic mean free path (DIIMFP) has contributions from bulk and surface plasmons. Monte Carlo simulation of the interaction of electrons with a solid medium and surface has been performed. The surface excitation parameter (SEP) is then obtained from the simulated reflection electron energy loss spectroscopy (REELS) spectra. The calculated SEP results by Monte Carlo simulation are compared with the previous calculations of total surface excitation probability, which was estimated by a numerical integration of surface term of DIIMFP. The contribution merely due to surface excitations towards REELS spectra is extracted by subtracting the two Monte Carlo simulated REELS spectra that based on the two models of electron inelastic scattering, i.e. a full surface model (SM) and a pure bulk model (BM). The surface excitations found to be significant at low energy losses and diminish at higher energy losses whereas the bulk plasmon contributions show opposite behavior and are negligible at lower energy losses. The average number of surface excitations is then evaluated by the computation of ratio of the integrated surface contribution to the elastic peak. The calculated results for Ag are found to be reasonably in agreement with our previous results for total probability of surface excitations and other reported experimental data for SEP. Surface correction factor (SCF) is calculated using SEP for several metals and is compared with the reported ratio of SCF with Ni sample as reference.

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