Diffraction and multichannel specular reflection of conductivity electrons by the surface of a metal

The influence of submonolayer ordered impurity films of oxygen, hydrogen or silver on the nature of the reflection of conductivity electrons by the surfaces of thin single crystal tungsten plates oriented in the (110) plane is investigated. The symmetry of adsorbed layers is controlled by low energy electron diffraction technique and the nature of conductivity electron reflection by the static skin-effect technique. It is shown that the interaction between the conductivity electrons and a surface covered by an ordered film is of a diffractional nature. The cases of multichannel specular reflection at the metal boundary which invole several nonequivalent states for the specularly reflected electrons are investigated in detail. The relation between the tangential components of the quasi-momenta of the incident and reflected electrons is determined by the Bragg relationship. The specularly reflected electrons are transferred in this case to physically equivalent points in phase space and also to other sheets of the Fermi surface. It is shown that such transitions (electron-hole transfer) may be ''switched on'' depending on the translational symmetry of the adsorbed film or during rotations of the inverse lattice surfaces with respect to the axes of the backing crystal. The plane symmetry varied as a result of variation of concentration of the impurity atoms