THE SURFACE ELECTRONIC-STRUCTURE OF STOICHIOMETRIC AND DEFECTIVE LIF SURFACES STUDIED WITH MIES AND UPS IN COMBINATION WITH AB-INITIO CALCULATIONS

UPS (He I) and metastable impact electron spectroscopy (MIES) spectra of the LiF(100) single crystal surface and stoichiometric LiF films ar e presented. The spectra are interpreted on the basis of ab-initio ele ctronic structure calculations. Defective surfaces, produced by electr on dosing, were studied in the same manner. The MIES spectra reveal th at the electron dosing produces metallic patches on the surface, but n o uniform Li adlayer. The calculations show that the F-center contribu tion to the electron emission is very close in energy to that from the metallic patches; thus, the two contributions cannot be distinguished by the present experimental techniques. (C) 1997 Elsevier Science B.V .