Spin Hamiltonian

Abstract

Abstract This chapter starts with an explanation of the different terms of the static spin Hamiltonian, their relation to structural parameters and a brief outline of the underlying physics of the various interactions. Then we discuss the transition amplitudes of electron and nuclear spin transitions and mention the most important line broadening mechanisms. Approaches to evaluate transition frequencies and line intensities of EPR and nuclear transitions from a given spin Hamiltonian are described in some detail. The concept of orientation selection by selective excitation, which is central for many pulse EPR experiments on disordered systems, is explained. Finally, we introduce a model system, which will be used in the following chapters to describe most of the pulse experiments devoted to the measurement of hyperfine interactions.