Excited Surface Band Structures and Surface Barrier Features in VLEED

Abstract

We have tested a surface barrier model for Cu(001) for consistency with below vacuum level data from inverse photoemission and above vacuum level data from very low energy electron diffraction (VLEED). The model has an exponential-type saturation which extends to the center of the first row of atoms in the crystal. The barrier model can account for the limited data available for the surface barrier band structure below the vacuum level but not for the strong surface barrier features which occur in VLEED reflectivity spectra for θ = 80° and ϕ = 45°. This is the case even when allowance is made for dynamical variation of the key barrier structural features. It is concluded that this form of the barrier saturation is not correct for real crystals.