Angle‐resolved synchrotron photoemission studies of clean and chemisorbed surfaces

Abstract

Ultraviolet photoemission spectroscopy (UPS) has been developed into an important tool in the study of solid surfaces and adsorbed over‐layers. Until recently, several important parameters in the photoemission process have been, at best, only imperfectly under the control of the experimenter. These are (1) photon energy, (2) optical polarization, and (3) momentum of the emitted electrons. Such limitations have concealed much information implicit in the flux of photoemitted electrons. Angle‐resolved UPS, combined with the continuum and polarization properties of synchrotron radiation, lifts these limitations to a large degree, and provides experimental evidence for three‐ and two‐dimensional band structure, surface states, and electronic and geometric properties of adsorbed species. We show some results of such experiments for clean and chemisorbed W. The data show a variable degree of complexity and, in general, may be analyzed only in the context of specific calculations.