BAND-STRUCTURE EFFECTS IN VERYLEED

In VeryLEED regime (below 30 eV) the spectra of electron reflection on the surfaces of crystals are dominated by the elastic effects of bulk E(k) above the vacuum level. This is revealed when the reflected inte nsity is found by matching on the surface the wavefunction in vacuum ( plane waves) and in the solid (Bloch waves). Following reflectivity fe atures versus energy and incidence angle, one can extract accurate and explicit information on upper E(k): the energies of extremes of bands along any Brillouin zone direction, and even whole bands along symmet ry lines. This is illustrated with a profusion of experimental example s. The theoretical background and the experimental technique are surve yed. Capabilities of VeryLEED to generate the upper bands for PES (IPE S) are outlined.