Orientation and alignment generated from photoionization of closed-shell cations

The orientation parameter A(10) and the alignment parameter A(20) have been calculated for the single photoionization of the closed-shell cations Na+, Al+, K+, Cu+, Ga+, Rb+, Ag+, In+, Cs+, Au+, TI+ and Fr+ where all possible vacancies from 2p(1/2) up to 6p(3/2) have been investigated. The calculations have been performed by employing a relaxed-orbital method within a single-configurational Hartree-Fock approach where mass-velocity and Darwin corrections have been incorporated into the non-relativistic approach. To cover the range, Of a possibly occurring Cooper minimum kinetic energies of the emitted photoelectron up to at least 20 Ry (approximate to 272 eV) have been considered. The results are compared with the orientation and alignment parameters of the respective singly photoionized isoelectronic atoms to underline differences in the strength of repulsive barriers and in the energetic position of shape resonances and Cooper minima. (C) 2004 Elsevier B.V. All rights reserved.