ABSTRACT
Figure 7.1 shows the various energy transfer and relaxation events that can occur following photo-excitation.
In this chapter, we explore the basis for excitation energy transfer between molecules. We begin with a discussion of irreversibility in a quantum mechanical system. We shall leave the molecular-level details of what causes this irreversibility for later, focusing our attention upon a phenomenological treatment in which we introduce in a rather ad hoc way the requisite decay times. Following this, we will consider how to compute the exciton coupling matrix element between molecular species using modern quantum chemical approaches.
