In this project in the Chemistry Division, Rodriguez will explore, quantify, and document the effect of a liquid or solid medium on the static and dynamic optical properties of porphyrins as well as on other comparable large molecules such as laser dyes. In this study, the dynamic and static optical properties of porphyrins in the vapor phase will be compared with those measured in the condensed phase using static and time-resolved methods that span the femtosecond- to second-time scales. Properties of interest include vibrational dynamics, charge-transfer processes, and van der Waals interactions with condensed-phase media. %%% Much of our present understanding of the behavior of large molecular systems is based on experimental data acquired on these molecules in liquid or solid hosts. However, the interaction of the molecules with the host can modify their behavior, and little effort has been devoted to document the magnitude of these effects. The results of these investigations under this Minority Initiation project will provide a framework for judging the effects of these media on various systems, including biologically important processes.