THE TRANSITION FROM QUANTUM TO CLASSICAL ATOM-SURFACE SCATTERING

We present a fully quantum mechanical model of atom-surface scattering which can be extended through the correspondence principle to the cla ssical limit. Calculations for comparison with recent He atom scatteri ng experiments on the Cu(001) surface show excellent agreement with th e observed diffuse inelastic backgrounds. The temperature dependence o f the scattering in the classical regime demonstrates conclusively tha t the He atoms exchange energy with a vibrating continuum interaction potential due to the surface electron density and not directly with a lattice of surface atomic cores.