Bloch-waves scattering theory is applied to photoemission from Mg(0001) up to photon energies of 320 eV. The quality of various approximations to the photoemission final state is analyzed based on the Fourier decomposition of the ab initio time-reversed scattering states. The relative importance of bulk and surface photoeffect in a one-dimensional pseudopotential model and in a real crystal is studied. The crucial role of the lateral umklapp scattering at high energies is revealed, and its implications for the stationary as well as for the attosecond time-resolved photoemission are discussed. The fine structure of the photoemission intensity distribution at high energies observed in earlier experiments is reproduced and explained.

• Received 23 September 2020
• Revised 17 November 2020
• Accepted 11 December 2020

DOI:https://doi.org/10.1103/PhysRevB.102.245139