Calculation of helium photoionisation with excitation to 2s and 2p levels including resonance structure

Abstract

Partial cross sections for photoionisation of He 1s2, leaving the ion in excited 2s and 2p levels, have been calculated. Resonance structure below the n=3 threshold due to doubly-excited autoionising states is included. The authors' calculation supports the result that, close to the n=2 threshold, the formation of ions in the 2p level dominates over the 2s level.