  Recently developed quantum mechanical theory of inelastic He atom scattering
(HAS) from solid surfaces is employed to analyze the energy transfer between
projectile particles (thermal energy He-atoms) and vibrational degrees of
freedom (phonons) characteristic of a variety of experimentally studied
surfaces. We have first calculated the angular resolved energy transfer which
can be directly compared with the values deducible from the HAS time-of-flight
spectra and a good agreement with experimental data has been found. This
enabled us to calculate the total or angular integrated energy transfer, which
is of paramount importance in the studies of gas-surface scattering, but is
neither accessible in HAS (which yields only the angular resolved quantities),
nor in the wind tunnel measurements for surfaces whose atomic composition and
cleanliness must be maintained during the experiment. Here we present the
results for prototype collision systems of this kind, viz. He => Cu(001), He =>
Xe/Cu(111) and He => Xe(111) which are representative of the very different
types of surface vibrational dynamics and thereby provide an insight into some
common properties of energy transfer in gas-surface scattering.

Statistical Mechanics