Relativistic effects in angle-resolved photoemission from Cu(110)

Abstract

Angle-resolved normal-emission photoelectron spectra of Cu(110) are calculated within the frame of the three-step model of photoemission with spin-orbit interaction included. Corresponding experimental spectra for linearly polarized light ($\ensuremath{\hbar}\ensuremath{\omega}=21.22$ eV) are presented and good agreement between theory and experiment is obtained. Spin-orbit coupling is important and gives rise to a detectable relaxation of single-group dipole selection rules even for materials with low atomic number. Since measured Cu(110) photoelectron spectra depend critically on the experimental angle resolution, care must be taken to seperate properly this intrinsic relativistic effect from those extrinsic effects originating from finite instrumental resolution. All features in the experimental spectra may be interpreted by direct interband transitions.