Ground state photoionization of copper-like thulium

Abstract

The R-matrix method has been applied to photoionization of copper-like thulium from its 4s 2Se ground state. Configuration-interaction wavefunctions were used to describe the initial bound and final continuum states. Up to seven states of the final Tm41+ ion were included in the wavefunction expansion. Total photoionization cross sections were calculated for a wide range of photon energies from the ionization threshold up to 350 Ryd. The background cross section increases thirtyfold as the 3De threshold is crossed. At low energies the cross section is dominated by several series of autoionizing resonances, which we have analysed in some detail. The authors have also calculated oscillator strengths for some transitions between the bound states of the Tm40+ ion. The calculations were performed in LS coupling.