Subshell coupling effects inL-shell ionization of gold by proton impact

The effect of subshell couplings on $L$-shell ionization cross sections for protons on gold has been estimated in the energy range 0.15-3 MeV. The applied model treats the couplings dynamically solving a set of coupled differential equations which govern the time evolution of the $L$-substate amplitudes. The effect has been found to be particularly large for the $L_2$ subshell, reaching 40% at low collision energies. The results of the calculations were used to correct the cross-section values obtained by Chen and Crasemann in the plane-wave Born approximation with use of Dirac-Hartree-Slater wave functions. The combined theory reproduces the structure observed recently by Jitschin et al. in the energy dependence of the $L_2$- and $L_3$-shell cross-section ratio.