Quantum-mechanical model for valence-electron emission from metal surfaces

Electron emission from the conduction band of metal surfaces is studied under grazing scattering conditions. We investigate this process making use of the quantum-mechanical (QM) model to represent the electronic interactions within the binary collisional formalism. The QM approach is based on the use of the model potential and allows us to describe the main features of the metal surface. It provides a precise description of both one-electron states and surface induced potential. In this work, the approximation is employed to evaluate electron distributions for 100 keV protons impinging grazingly on the Al(111) surface. We have found that the realistic representation of the surface included in the QM model introduces substantial changes in the valence emission at low electron energies and intermediate ejection angles. The influence of the surface wake potential on the valence emission probability is also addressed. In order to compare with experiments, we add the contribution coming from atomic inner shells calculated with the field-distorted-wave approximation. Total theoretical results obtained with the QM model are in fairly good agreement with the available experimental data.