Ju-Tang Hsiao

Doubly excited states of the Be atom in the MCRRPA

Photoionization parameters in neutral beryllium are calculated in the multiconfiguration relativistic random-phase approximation to resolve the interplay between relativistic and correlation effects in low-Z atoms or ions. Precise energies and widths of all five Rydberg series of low-lying doubly excited states (2pns)3,1Po1, (2pnd)3,1Po1 and (2pnd)3Do1 are given. Experimental studies on angular distribution of photoelectrons are suggested to obtain information on widths of some states, which cannot be obtained from total cross-section measurements.

Applications of the relativistic equation of motion to photoionization of Mg-like ions

Abstract As an approximation to the relativistic equation of motion, the multiconfiguration relativistic random-phase approximation theory is applied to the valence-shell photoionization of the Mg-like ions. Photoionization cross sections between ( 2 p 6 3 s ) 2 S 1 / 2 and ( 2 p 6 3 p ) 2 P 1 / 2 0 ionization thresholds are calculated. The main feature of our results is exhibited by five Rydberg series of doubly excited states arising from fine-structure splittings. A comparative study of Al + , Si 2+ , P 3+ , S 4+ , Cl 5+ , and Ar 6+ is presented.

Angular and polarization correlations in double-excitation resonances of Mg

Angular distribution and spin polarization of photoelectrons from 3s valence subshell of neutral magnesium are investigated by using the multiconfiguration relativistic random-phase approximation. Photoionization parameters for all five Rydberg series of double-excitation resonances P1o, P1o, and 3D1o between the Mg+[3s] and Mg+[3p] thresholds are presented to clarify the high-energy portion of the Rydberg series, in which peaks corresponding to double excitations can be identified unambiguously.

Photoionization Processes of the Single-Ionized Boron

The relativistic calculations of the cross-section , the angular-distribution parameter , and spin-polarization parameters of photoelectrons using the multiconfiguration relativistic random-phase approximation theory for the photoionization of the ion are presented. Precise energies and widths of all five Rydberg series of doublyexcited states , , , , and are determined. Our predictions are in very close agreement with experiments and are consistent with other calculations.

Photoionization of Be, B+, C2+, N3+, O4+, and F5+ in the MCRRPA theory

The multiconfiguration relativistic random-phase approximation theory is applied to the valence-shell photoionization along the Be isoelectronic sequence. Photoionization cross sections between (1s22s)2S1/2 and (1s22p)2P°1/2 ionization thresholds are calculated. There are five Rydberg series of doubly excited states that manifest themselves as autoionization resonances in the photoionization cross section. A comparative study of Be, B+, C2+, N3+, O4+, and F5+ is presented.