Étude d'une surface de NaCl (100) par diffraction inélastique d'électrons lents

Abstract

A NaCl cleaved in UHV surface is studied by low energy electrons spectroscopy. First, elastic and inelastic diffraction (ELEED, ILEED) are investigated. The intensityvoltage spectra are plotted. On ELEED intensity profiles, primary and secondary Bragg peaks are observed. On ILEED intensity profiles, a two-peaked structure is showsd, this splitting is explained by a “two-step”process: the first peak is associated with those electrons whose elastic diffraction is followed by an inelastic scattering, the second one with electrons whose inelastic scattering is followed by elastic diffraction. Then studies about identification of the inelastic process observed in ILEED spectra, are reported. Angular profiles, taken at a number of different primary energies, are plotted. Some of them are single peaked, others split into two peaks. We think that these structures are due to the excitation of surface and volume plasmons. The behavior of these profiles is that expected of plasmons, if one considers a kinematic model of inelastic diffraction. In a special case, the surface plasmon angular distribution shows the influence of a particular surface defect.