QUANTUM STOCHASTIC APPROACH FOR MOLECULE SURFACE SCATTERING .2. ADSORPTION RESONANCES OF HE ATOMS ON XE OVERLAYERS/

He scattering from Xe monolayers adsorbed onto Ag substrates is studie d using a quantum stochastic method. Both the He atom and the surface and bulk modes are treated quantum mechanically using a mean-field par titioning of the quantum Liouville equation. The resulting equations o f motion permit the evaluation of the reduced density matrix of the He atom subsystem by averaging over a series of ''quantum trajectories.' ' The final reduced density matrix of the atomic subsystem, when proje cted onto the asymptotic states, provides an accurate estimate of ener gy transfer processes between the atom and the surface. Our calculatio ns indicate that inelastic energy transfer is enhanced near adsorption resonances due primarily to the increased lifetime of the atom near t he surfaces as evidenced by marked deviations from the Debye-Waller th ermal attenuation rates.