Autoionisation states in neon: photoionisation from ground and excited states

Abstract

A multiconfiguration close-coupling calculation of the photoionisation of the ground state and low-lying 1Se excited states of neon has been made using a Ne+ target based on orbitals from the optimised potential model. The final-state energies considered extend from threshold into the region of the lowest autoionisation state resonances whose shapes were calculated and found to compare well with experiment where comparison is possible. The largest of the calculated resonances, originating from an excited state, peaks at over 5*101-15 cm2 which is about three orders of magnitude higher than when excited from the ground state. Oscillator strengths for certain bound-bound transitions, and near-threshold cross sections exhibiting d-channel minima for photoionisation of the excited states are also given. Finally, further development of the complex-amplitude analysis of the photoionisation at the resonances is described.