Surface structure angle-resolved photoelectron emission

Given adequately prepared surfaces, angle-resolved photoemission and the various yield spectroscopies have been used to investigate filled and empty surface states, respectively. Results of angle-resolved photoemission measurements have been published by Knapp and Lapeyre [181], Williams et al. [182], Knapp et al. [183] and Huijser et al. [184], A typical set of angle-resolved photoelectron energy distributions (AREDCs) due to Huijser et al. [184] is shown in Fig. 16, in which four structures labelled B , SM S2 and B2 are observed. They are ascribed to emission from filled intrinsic states since they disappear on exposure to 10s L of H2. As we shall see below, B , S and S2 are primarily As-derived, while B2 is mainly a Gas-like state bonded to Asp-states. 

A particularly useful variety of UPS is angle-resolved photoelectron spectroscopy (ARPES), also called angle-resolved ultraviolet photoelectron spectroscopy (ARUPS) [, 62]. In this technique, measurements are made of the valence band photoelectrons emitted into a small angle as the electron emission angle or photon energy is varied. This allows for the simultaneous determination of the kinetic energy and momentum of the photoelectrons with respect to the two-dimensional surface Brillouin zone. From this information, the electronic band structure of a single-crystal material can be experimentally determined. 

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