Cross sections forL-subshell ionization in Au by the collision of protons and helium ions

Abstract

Absolute ionization cross sections for the $L$ subshells of Au by proton bombardment (0.25-5.2 MeV) have been determined from data obtained using a Si(Li) detector and the presently available values for radiative transition probabilities, fluorescence yields, and Coster-Kronig factors. The measured cross sections are compared with values calculated by Choi using the plane-wave Born approximation (PWBA) with either relativistic or nonrelativistic hydrogenic wave functions for the Au electrons. Except at low energies ($\frac{{\eta }_L}{{\theta }_L^2}<0.2\mathrm{}$) where the uncorrected PWBA is questionable, the agreement is good. A plateau in the $2s$ ionization cross section attributable to the bimodal $2s$-electron wave function is observed in the region 0.5-1.0 MeV. Ionization by He ions (1-12 MeV) is similar, but significant differences in subshell behavior are observed.