Chapter 7: The Local Work Function of Thin Metal Films: Definition and Measurement

Abstract

Publisher Summary This chapter discusses the “local work function” and describes a simple but powerful technique to measure local work functions on an atomic scale—namely, the photoemission of adsorbed xenon (PAX). It is generally accepted that the work function is the difference in potential energy between an electron at the Fermi and the vacuum level, respectively. The existence of a “local” work function is sometimes questioned with the argument that the work function is related to the chemical potential, which is overall the same in a body in equilibrium. This is true for the Fermi potential but not necessarily for the work function, which is the difference between two potentials. Another argument is that the surface dipole contribution to the work function as an electrostatic potential cannot be “localized.” This argument is incorrect because the electrostatic surface potential at a given point in space near a metal surface depends on the surface charge density.