EXPERIMENTAL AND THEORETICAL CROSS-SECTIONS FOR PHOTOIONIZATION OF METASTABLE AR-ASTERISK AND KR-ASTERISK ATOMS NEAR-THRESHOLD

Using high-resolution laser photoelectron spectrometry we have determi ned absolute cross sections sigma(J0J1) and the electron angular distr ibution parameter beta(J0J1), for one-photon ionization of metastable Ar(J(0) = 0, 2) and Kr*(J(0) = 0, 2) atoms to the resolved J(1) = 3/2 , 1/2 ion states near threshold (lambda = 351-244 nm). For comparison with the experimental data we have carried out many-electron calculati ons of the relevant partial cross sections and beta parameters over th e photoelectron energy range (0-6 eV). We have used a configuration in teraction 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 betwee n the theoretical and experimental results. Including previously repor ted cross sections for metastable Ne and Xe* atoms we present a discu ssion of the trends which are observed in the different energy-depende nt cross sections as a function of the atomic number.