SURFACE SCATTERING OF THERMAL-ENERGY HE BEAMS - FROM THE PROOF OF THE WAVE NATURE OF ATOMS TO A VERSATILE AND EFFICIENT SURFACE PROBE

The first conclusive molecular beam scattering experiment on surfaces has been performed in 1915 by Knudsen. This and a few other classical experiments which led to the modern period will be outlined, and the conclusions drawn from these experiments as well as their influence on the further development will be discussed in the first part. In the second part, the three main modes in which He-beams are currently used as a probe for surface investigations are commented on, with emphasis on the study of disordered surfaces.