Note on the necessity of relativistic dipole selection rules in photoemission

Abstract

In a recent study of normal photoemission from Ag(111) Borstel et al. [Phys. Rev. B 23, 3121 (1981)] conclude that a consistent interpretation requires the use of relativistic dipole selection rules even for elements of low atomic number where spin-orbit splittings are too small to be detected by photoemission experiments. To check these ideas we have studied polarization-dependent photoemission from Cu(110), Cu(111), Ag(110), and Ag(111). We show that our results and also the data of Borstel et al. which are reproduced experimentally may be interpreted in terms of nonrelativistic dipole selection rules.