ELFT HÍRADÓ

[Hajnal Zoltán <hajnal AT mfa.kfki.hu>]

Dear Colleague,

the Research Institute for Technical Physics and Materials Science (MTA
MFA) invites you to the extraordinary seminar 

on Tuesday, 11 October 2005, at 11:00 at the lecture room (Tanácsterem)
of the MFA (Bldg. 26, KFKI campus, Budapest)

Program:

1.      Dr. I. Bársony (MFA Director) salutes Prof. A. Jabłoński
        and honours our guest with the MFA Medal

2.      Guest Talk:
        
        Prof. Aleksander Jabłoński 
        Institute of Physical Chemistry
        Polish Academy of Sciences (PAN), Warszawa, Poland

        "Evaluation of elastic-scattering cross sections 
        for electrons and positrons over a wide energy range"

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 describing 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 [1]. 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. 

Comparisons of calculated differential elastic-scattering cross sections
(DCSs) for silicon and gold at selected energies relevant to AES, XPS,
EPMA, and AEM are reported. The considerable difference between the DCSs
for electrons and positrons is indicated and discussed. A significant
influence of the electron-exchange correction, correlation-polarization
correction, and absorption correction is found at electron energies
characteristic for surface-sensitive electron spectroscopies. These
effects are quantified for selected cases.

[1] Salvat F, Jablonski A, Powell CJ. Comput. Phys. Commun. 165, 157
(2005).