Introduction

In this chapter we investigate the electronic properties of clean solid surfaces. Certainly this is a prerequisite to any fundamental understanding of the electrical behavior of surfaces and interfaces. However, it also is essential to a coherent view of other surface phenomena, viz., oxidation, heterogeneous catalysis, crystal growth, brittle fracture, etc. There is no question that applications such as these provide most of the impetus behind surface science research. Nevertheless, we restrict ourselves here to only the most basic physics questions. What is the charge density in the neighborhood of the vacuum interface? Are the electron states near the surface different from those in the bulk? How do chemical bonding states in the first few atomic planes rearrange themselves after cleavage? What is the electrostatic potential felt by surface atoms?

The principal experimental probe of these issues is photoelectron spectroscopy and we will have much to say about this technique below. It turns out that the relevant measurements are relatively easy to perform but that the interpretation of the data is not entirely straightforward. It is helpful to have some idea of what to expect. Therefore, we defer our account of the experimental situation and proceed with some rather general theoretical considerations.

The methods of surface electronic structure are the same as those used to analyze the corresponding bulk problem.