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A: Atomphysik

A 10: Posters Wednesday (Cooling and Trapping, Electron Scattering and Recombination)

A 10.20: Poster

Mittwoch, 4. April 2001, 12:30–15:00, AT3

Critical minima in elastic electron scattering from argon — •J.E. Sienkiewicz, S. Telega, and V. Konopińska — Katedra Fizyki Teoretycznej i Metod Matematycznych, Politechnika Gdańska, Pl-80-952 Gdańsk

Relativistic ab initio calculations of both – low and high angle – critical minima in the differential cross sections for elastic electron scattering from argon are presented. Theoretical approach is based on the Dirac-Hartree-Fock method. Exchange between incident and target electrons is calculated exactly. Target polarization is described by ab initio potential taken from relativistic polarized orbital calculations. Position of our critical minima (39.3 eV,68^∘) and (39.5 eV,141^∘) agree well with recent measurements of Panajatovi/c et al (1997).

The positions of critical minima are very sensitive to the chosen theoretical and experimental methods. Another significance of critical minima lies in the fact that their positions indicate the highest - reaching unity - spin polarization of scattered electrons.

Two other minima pointed out by Kessler et al (1976) as separate critical minima are lying very close to our high-angle minima position curve. Our calculations of critical minima depths show that the first one is deeper. Our results allow for theoretical verification of experimentally obtained critical minima.