Selective adsorption and interaction potential of He/Xe-Graphite

We studied the selective adsorption for He atom scattered from a (√3 × √3)R30° ordered layer of xenon adsorbed on the graphite (0001) surface. From the angular position of bound state resonance structures in the specular intensity, the laterally averaged potential V0(z) is found to give rise to three discrete levels with energies of 4.83, 1.99 and 0.66 meV. The energy levels are used to derive information on the helium-rare gas overlayers potential. V0(z) is found to be well represented by a sum of pair interactions U(r−Rj) between the He atom and the Xe atoms plus the long range interaction of He atom with the graphite substrate.