The evaluation of configuration coordinate parameters from high pressure absorption and luminescence data

A configuration coordinate model was previously developed for relating the energies involved in optical and thermal electron excitations between two states and the effect of pressure on these energies. In the course of this development, expressions were presented for hv(max), the optical absorption peak maximum, and (E((1/2)))(a) the peak half-width, as functions of pressure, and of the parameters defined in the model. The analysis was later extended to emission. We elaborate on the equations for the change of hv(max) and E((1/2)) with pressure and discuss some of the problems involved in evaluating and using peak half-widths. Various combinations of absorption and emission data for evaluating the parameters describing the excitation are discussed and are compared for phenanthrene in various environments.