Distorted-Wave Calculations of Triple Differential Cross Section for Inner Shell Ionization

Abstract

Distorted-wave impulse approximation (DWIA) and distorted-wave Born Approximation (DWBA) calculations are presented for inner shell ionization of Ar(2s), Ar(2p) and Ne(1s) in the incident energy range 2–3 keV and for Ar(2p) at 8 keV. Comparison is made with the relative experimental data of Bickert and Hink (1989) and Bickert et al (1990, 1991 a,b) and with the absolute measurements of Lahmam-Bennani et al (1984). For on-Bethe-ridge kinematics at high enough incident energy DWIA often gives better agreement with experiment than previous first Born type theories. This implies that conclusions about the factorization approximation drawn from work on outer shell ionization (Madison et al 1989, McCarthy 1992) are still tenable for inner shell ionization, provided that the incident energy is high enough. However, the best approximation is DWBA which excellently reproduces all of the experiments both in shape and magnitude. The results show the importance of taking proper account of the strong static-exchange potential of a “heavy” atom, particularly in inner shell ionization which takes place in a region where the static-exchange potential is strong.