On the scattering mechanism of the electron impact on surfaces in specular reflection geometry : Nickel (110)

Lately several (e,2e) experiments on surfaces have been performed under specular reflection geometry. To ascertain the dominant interaction mechanism is of key relevance in order to derive, from these experiments, the correct information on the target electronic structure. This can be done performing a simple angle resolved energy loss experiment instead of a complex coincidence one. Elastically and inelastically specularly reflected electrons have been measured as a function of the primary electron kinetic energy (IV curve) on graphite and Ni. The incident beam energy was varied between 150 and 450 eV. Several IV curves, each one at fixed energy loss between 6 and 35 eV, have been collected. These results show that an inelastic scattering is always accompanied by an elastic one giving rise to two independent channels : the elastic event follow (L+D) or precede (D+L) the inelastic one. They also indicate that none of the two channels dominates over the other irrespective of the degree of localization of the excitation involve