Introduction

The opening chapters of this book have shown how the hyperfine interactions which give rise to the Mössbauer spectrum are a means by which the electronic environment of the nucleus may be examined. The preceding chapter in particular has shown how the Mössbauer parameters can be related to various aspects of chemical bonding and the geometrical properties of compounds. In this chapter the application of Mössbauer spectroscopy in the examination of electronic, molecular, and lattice structure will be considered. Given the close connection between electronic structure and chemical bonding, which has been covered in Chapter 2, this chapter will devote particular attention to molecular and lattice structure, which are both properties amenable to investigation by Mössbauer spectroscopy.

The interpretation of the Mössbauer spectrum obtained from a molecular solid is highly dependent on the particular situation. For example, in some cases two inequivalent Mössbauer atoms may be involved in the molecular complex and this can provide a means by which the Mössbauer data may be more comprehensively interpreted. However, in the majority of compounds studied by Mössbauer spectroscopy only one Mössbauer atom is present and, while acknowledging the advantages of having such a sensitive probe of the immediate local environment, there are often problems in making conclusions concerning the number or disposition of the atoms or groups around the Mössbauer atom.