Extracting the surface barrier structure from very low-energy electron-diffraction (VLEED) reflectivities

Full text: Fine structure in VLEED reflectivity data near beam emergences arises from scattering at the surface potential barrier. For metals, including Cu(001), many studies have attempted to analyse this data to obtain, particularly, the origin zo from the image potential which exists at metal surfaces, as well as the saturation from image barrier form closer to the surface. For Cu(001), analyses from 1979 to 1999 have stated determinations of zo from -1.3 ± 0.3 a.u. to -3.2 ± 0.2 a.u. from the centre of the top layer of atoms with some data fits also for zo as large as 3.7 a.u. This paper explores why such differing sets of results have been obtained and how one can successfully extract definitive information of the surface barrier structure from high resolution VLEED data