ELECTRON MOMENTUM SPECTROSCOPY OF SOLID-SURFACES

The valence electronic structure of materials with crystalline order i s described by the energy-momentum dispersion laws and densities of el ectron bands. These quantities are directly observed for the surfaces of thin (about 100 Angstrom) solid films by electron momentum spectros copy, based on kinematically complete observations of ionization event s. The principles of the experiment and the imperfections of the probe are described and illustrated by examples. Comparison is made with ot her electron spectroscopies that measure subsets of the complete energ y-momentum density information.