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

Very-low-energy electron diffraction (VLEED) intensities from clean Cu (111) surface have been measured in detail in the energy range 15 to 3 5 eV by low-energy electron microscope. Corresponding theoretical I-V curves are obtained in good agreement with experimental data when the anisotropy of the electron attenuation is taken into account. The coin cidence of the peaks in the I-V curves at normal incidence with two ki nds oi energy gaps of the electron band structure of the copper crysta l (E-k parallel to=0) is interpreted. The small width of the resonance peak in the I-V curve at normal incidence is explained in terms of el ectron surface channeling. VLEED thus provides information about the u noccupied part of the electron band structure of copper which compleme nts that obtained from angular resolved photoemission.