Experimental and theoretical cross sections for photoionization of metastable Ne*(3s P-3(2), P-3(0)) atoms near threshold

Using high-resolution laser photoelectron spectrometry we have determined for the first time absolute cross sections sigma(J0J1) and the electron angular distribution parameter beta(J0J1) for one-photon ionization of metastable Ne*(3s P-3(J0), J(0) = 2, 0) atoms to the resolved Ne+(P-2(J1), J(1) = 3/2, 1/2)) ion states near threshold (lambda = 244 nm) as well as the beta-parameter for metastable He* (2(3)S(1), 2(1)S(0)) atoms at lambda = 244, 257.25 nm. For comparison with present and future experimental data we have calculated partial cross sections and beta-parameters for photoionization of Ne*(3s, J(0) = 2,0), and of the analogous alkali atom Na(3s) over the photoelectron energy range 0-10 eV. We have used both a term-dependent Hartree-Fock approach and a configuration-interaction method involving Pauli-Fock atomic orbitals (CIPF); the latter was designed to take into account the important electron correlation effects which are found to be essential for obtaining good agreement between the theoretical and experimental results.