Photoionization of4felectrons from rare-earth atoms at a surface

Measurement of photocurrent versus frequency of $4f$ electrons from surface-rare-earth atoms is proposed as a means for identifying refraction effects in photoelectron spectroscopy. The idea of using surface-rare-earth-atom $4f$ electrons takes advantage of the fact that since their wave functions are atomiclike (even though their binding energies are typically only a few eV) any unusual behavior of the photoyield versus frequency will not be ascribable to poorly known surface-electron wave functions, but will have to be associated with dielectric interface effects. Jellium-model calculations are presented which show qualitatively how surface dielectric phenomena should appear in the frequency variation of the ratio of photoyields with $p$-polarized and $s$-polarized light.