In recent decades surface science has experienced a large growth in
connection with the development of various experimental techniques which
are able to characterize solid surfaces through the observation of the
scattering of ions, electrons, photons or atoms. These methods of
investigation, known under different labels such as LEED, AES, XPS, UPS,
etc. have been extensively applied in describing the structure,
morphology, and chemical and physical properties of crystal surfaces and
interfaces of a large variety of materials of interest in solid-state
physics, electronics, metallurgy, biophysics, and heterogeneous
catalysis. Among these methods we wish to emphasize molecular beam
scattering from solid surfaces. lolecular beam scattering has gone
through a large development in the last ten years. In this decade a
large number of laboratories have used this method to study various
clean and adsorbate-covered surfaces. The technique is nonetheless quite
old. It dates back to the beginning of the thirties, when Estermann and
Stern performed the first atom diffraction experiment proving the wave
nature of atoms. In the following years the entire subject of
gas-surface interaction was considered a branch of rarefied gas dynamics
and developed in connection with aerospace research. Attention was then
given to the integral properties of gas-solid interactions (sticking and
energy accomodation, mean momentum transfer) rather than to atom-surface
scatter- ing from well-characterized surfaces.