Publication

Abstract : Photoionization cross sections and dipole angular distribution asymmetry parameters, β, of 5s and 4d shells of the closed-shell ions (La3+,La9+, and La11+) in the La isonuclear sequence have been studied using the relativistic random phase approximation. The positions of the 5s Cooper minima in La3+ and La9+ ions are found to be extremely sensitive to the details of electron correlation. The results show that the 5s cross sections of La3+ and La9+ do not lie along the same curve near the thresholds; the 4d cross sections, however, do match well in overlap regions so they lie along the same curve, over the isonuclear sequence, except for a shift in threshold towards higher energies with increasing degree of ionization.