CU(111) ELECTRON BAND-STRUCTURE AND CHANNELING BY VLEED

Very-low-energy electron diffraction (VLEED) intensities from dean Cu( 111) surface have been measured in derail in the energy range 15-35 eV by low energy electron microscope. Corresponding theoretical I-V curv es are obtained in good agreement with experimental data when the anis otropy of the electron attenuation is taken into account. Coincidence of peaks in the I-V curves at normal incidence with two kinds of energ y gaps of the electron band structure of the copper crystal (E(k paral lel to=0)) is interpreted. The small width of the resonance peak in th e I-V curve at normal incidence is explained in terms of electron surf ace channeling.