Experimental and theoretical cross sections for photoionization of metastable and atoms near threshold

Abstract

Using high-resolution laser photoelectron spectrometry we have determined absolute cross sections and the electron angular distribution parameter for one-photon ionization of metastable and atoms to the resolved ion states near threshold -244 nm). For comparison with the experimental data we have carried out many-electron calculations of the relevant partial cross sections and parameters over the photoelectron energy range (0-6 eV). We have used a configuration interaction method involving Pauli-Fock atomic orbitals (CIPF), designed to take into account the important electron correlation effects which are found to be essential for obtaining satisfactory agreement between the theoretical and experimental results. Including previously reported cross sections for metastable and atoms we present a discussion of the trends which are observed in the different energy-dependent cross sections as a function of the atomic number.