COUPLED-STATES CALCULATIONS OF ARGON L-SHELL IMPACT IONIZATION
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abstract
Uses a coupled-states method to calculate the corrections to the first Born approximation for L-shell impact ionisation. The specific collisions considered are p+Ar and alpha +Ar, at energies between 100 and 850 keV amu-1. The method, which uses a classical projectile path and a pseudostate description of the ionisation continuum, has previously been applied to K-shell impact ionisation. The pseudostate and partial-wave convergence is considered in detail. It is found that more partial waves are needed than for K-shell ionisation, but not so many as to make coupled-states calculations intractable. The authors observe that the absolute cross sections for these collisions are sensitive to the particular independent-particle-model (IPM) target-atom potential which is used. They consider different IPM target potentials for use in ionisation theory, and propose a modification to the long-range part of the neutral-atom Hartree-Fock (HF) potential that lowers the energy of the unbound pseudostates and that thereby brings the L-shell removal energies closer to the experimental ionisation potentials.
