Theoretical description of the Fano-effect in the angle-integrated valence-band photoemission of paramagnetic solids

A theoretical description of the Fano-effect in the angle-integrated valenc e-band photoemission (VB XPS) of paramagnetic solids is presented that is b ased on the one-step model of photoemission and relativistic multiple scatt ering theory. Applications to fcc-Cu and fcc-Ag led to a very satisfying ag reement with recent experimental data that show the Fano-effect, i.e., a fi nite spin polarisation of the photoelectrons is found for excitation with c ircularly polarised radiation. As can be demonstrated by model calculations , this finding is caused by the presence of spin-orbit coupling. To allow f or a more detailed discussion of the spectra, a simplified description of t he Fano-effect is presented that treats spin-orbit coupling as a perturbati on.