High resolution electronic spectroscopy of large polyatomic molecules: Structures, interactions and electronic distributions

Rotationally resolved fluorescence excitation spectroscopy has been used to investigate both the structures and electronic characteristics of biologically relevant polyatomic molecules and the clusters in the environment of a supersonic jet expansion. The high resolution spectra have provided accurate and precise three-dimensional molecular structures for both ground (S0) and excited (S1) electronic states, and the corresponding electronic transition moment orientation. These studies gave detailed information about the preferred geometrical conformation of the molecules and have allowed insightful information of their interactions with water. Subsequently, the parameters extracted from the fit of these electronic spectra to characterize the electronic landscape for these biomolecules allow an unambiguous description of the conformational landscape. In addition, these experiments have allowed us to investigate the factors that influence the electronic organization upon excitation. All of this information is extended to the development of models to understand and characterize systems of chemical and biological essence.