Chapter 3 The Use of Ex-situ UHV Techniques to Study Electrode Surfaces

Abstract

This chapter discusses the use of ex-situ ultra-high vacuum (UHV) techniques to study electrode surfaces. At a metal or semiconductor surface in contact with an electrolyte, the elementary charge-transfer reaction occurs in a region of space of the order of 1 nm thick or less. Electrochemists have developed a range of highly sensitive techniques to observe changes in the composition of the interphase that can detect amounts at least as small as 1% of a monolayer in terms of the charge exchanged. They are also capable of giving some information about the nature and strength of bonding of interfacial species by the position of the response on the potential scale, especially when the charge exchange is rapid. The alternative route to the solution of the problem of surface structure and composition is the one to be described in the chapter as the ex-situ route. By transferring the electrode from the electrochemical cell into the UHV, a vast range of techniques developed in the past two decades by surface scientists becomes available, notably those which depend on electron spectroscopy or electron diffraction.