Evaluation of Elastic-Scattering Cross Sections for Electrons and Positrons Over a Wide Energy Range

Published

September 1, 2005

Author(s)

Aleksander Jablonski, Francesc Salvat, Cedric J. Powell

Abstract

Quantification of surface and bulk analytical methods, e.g., Auger-electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), electron-probe microanalysis (EPMA) and analytical electron microscopy (AEM), requires knowledge of reliable elastic-scattering cross sections for deccribing electron transport in solids. Cross sections for elastic scattering of electrons and positrons by atoms, ions, and molecules can be calculated with the recently developed code ELSEPA (ELastic Scattering of Electrons and Positrons by Atoms) for kinetic energies of the projectile from 10 eV to 100 MeV. These calculations can be made after appropriate selection of the basic input parameters: electron density distribution, a model of the nuclear charge distribution, and a model for the electron-exchange potential (the latter option applies only to scattering of electrons). Additionally, the correlation-polarization potential and an imaginary absorption potential can be considered in the calculations.We report comparisons of calculated differential elastic-scattering cross sections (DCSs) for silicon and gold at selected energies relevant to AES, XPS, EPMA, and AEM. The DCSs for electrons and positrons differ considerably, particularly for medium- and high-atomic-number elements, and kinetic energies below about 5 keV. The DCSs for positrons are always monotonically decreasing functions of the scattering angle, while the DCSs for electrons have a diffraction-like structure with several minima and maxima. A significant influence of the electron-exchange correction is observed at 500 eV. The correlation-polarization correction is significant for small scattering angles at 500 eV, while the absorption correction is important at energies below about 5 keV.

Citation

Surface and Interface Analysis

Volume

37

Pub Type

Journals

Keywords

analytical electron microscopy, Auger electron spectroscopy, differential cross sections, elastic scattering, electron-probe microanalysis, electrons, gold positrons, silicon, x-ray photoelectron spectroscopy

Citation

Jablonski, A. , Salvat, F. and Powell, C. (2005), Evaluation of Elastic-Scattering Cross Sections for Electrons and Positrons Over a Wide Energy Range, Surface and Interface Analysis (Accessed May 1, 2024)