Spin-orbit splitting of image states

We quantify the effect of the spin-orbit interaction on the Rydberg-like series of image state electrons at the (111) and (001) surfaces of Ir, Pt and Au. Using relativistic multiple-scattering methods we find Rashba-like dispersions with ΔESO(K) = γK with values of γ for n = 1 states in the range 38-88 meV A. Extending the phase accumulation model to include spin-orbit scattering we find that the splittings vary like 1/(n+a)3, where a is the quantum defect, and that they are related to the probability of spin-flip scattering at the surface. The splittings should be observable experimentally, being larger in magnitude than some exchange splittings that have been resolved by means of inverse photoemission, and are comparable to linewidths from inelastic lifetimes