Angle-resolved photoemission from copper: Prediction of spectral peak intensities

Abstract

Angle-resolved photoemission spectra computed from a recently developed theory, which utilizes a plane-wave final state but matrix elements based on atomic-like dipole selection rules, are shown to compare well with data obtained from a Cu(111) surface for $h\nu =11.8\mathrm{} \mathrm{to} 40.8$ eV. Constant matrix elements and matrix elements calculated from a single-plane-wave final state are found to be inadequate for describing the spectra. It is shown that the sensitivity of the shape of the spectra to the relaxation of the component of momentum perpendicular to the surface allows an estimate of the mean free path to be made. Emission from the so-called surface state located at 0.3 eV below the Fermi energy is explained by a one-dimensional singularity in the bulk bands. The variation of the spectra with polarized light is shown to be of value in separating the initial-state bands contributing to the spectra in any one direction.