Experimental methods of HAS surface phonon spectroscopy

Abstract

Helium Atom Scattering (HAS) and Electron Energy Loss Spectroscopy (EELS) are the major experimental surface scattering techniques which have provided during the last decades information on the energies and dispersion curves of surface phonons. The projectiles, either a He atom or an electron are inelastically diffracted in a coherent fashion from the phonon wave oscillations at the surface of the target. In this chapter the kinematics, the intensities, the apparatus and the resolution of HAS experiments are discussed in detail, with quantitative comparisons with EELS experiments.