Giant spin-orbit interactions in Ar photoionization

We have performed a highly correlated R-matrix calculation for the photoionization of Ar which includes the spin orbit interaction in order to account for the observed giant resonances in the photoionization cross sections of the LS forbidden quartet satellite states of Ar+ as well as those for the dipole allowed doublet states. Contrary to the experimental finding that the cross sections for the 3p4 (3P)4p 4D1/2 and 3p4 (3P)4p 4D3/2 quartet states were 16 to 30 times larger than the doublet states over certain regions, our results reflect the expected result that the doublet states cross sections dominate.