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.