Importance of relativistic interactions in photoemission of high angular momentum electrons in mercury

The authors have studied the interplay between potential barrier effects, exchange terms and relativistic interactions in photoemission processes involving high angular momentum subshells (nd 5/2 , nd 3/2 with n=4 and 5, 4f 7/2 and 4f 5/2 ) of mercury. Ab initio calculations of various photoemission cross sections, angular distribution parameters and phaseshifts of the corresponding continuum wavefunctions are performed in jj coupling, using the Dirac-Slater approximation. The physical origin and the importance of spin-orbit effects are established in the framework of the angular momentum transfer theory which shows that, in these cases, the spin-orbit effects introduce extra values of the transferred angular momentum and manifest themselves as anisotropic interactions as the photoelectron escapes from the core. The authors show that they are greatest in the channels nl 4l+1 l-1, because of the existence of an intense repulsive potential barrier in the channels nl 4l+1 l+1. In the latter, the excited orbitals may be not penetrating enough to mix both singlets and triplets before the photoelectron energy has gained enough energy so that the influence of relativistic interactions may be delayed.