Study of Gas-Graphite Potential by Means of Helium Atom Diffraction

Abstract

Scattering of thermal He atoms from a low-temperature graphite (0001) surface was carried out. The measured diffraction pattern shows that the repulsive part of the periodic gas-surface potential is rather well represented by the first Fourier component. The "hard wall" peak-to-peak spatial modulation is 0.21 \AA{}. Bound-state resonances allow one to determine four distinct energy levels of the laterally averaged potential well. A comparison with available adsorption data is presented.