GROUND-STATE PHOTOIONIZATION OF COPPER-LIKE THULIUM

The R-matrix method has been applied to photoionization of copper-like thulium from its 4s 2S(e) ground state. Configuration-interaction wav efunctions were used to describe the initial bound and final continuum states. Up to seven states of the final TM41+ ion were included in th e wavefunction expansion. Total photoionization cross sections were ca lculated for a wide range of photon energies from the ionization thres hold up to 350 Ryd. The background cross section increases thirtyfold as the 3D(e) threshold is crossed. At low energies the cross section i s dominated by several series of autoionizing resonances, which we hav e analysed in some detail. We have also calculated oscillator strength s for some transitions between the bound states of the Tm40+ ion. The calculations were performed in LS coupling.