Chapter 5 - Structures and Dipole Moments of Molecules in Their Electronically Excited States

Abstract

Light driven changes of molecular dipole moments are vital for the understanding of solvent reorientation or relaxation of a solute, or the reorientation of the local protein surrounding of electronically excited aromatic amino acids. Furthermore, explication of resonance energy transfer processes like Förster Resonant Energy Transfer (FRET) and molecular excitonic interactions, which are the basis for the understanding of energy and charge transport phenomena rely on the knowledge of the magnitude of light induced dipole changes. High resolution electronic Stark spectroscopy offers a valuable tool for an exact determination of both magnitude and direction of dipole moments in both electronic states connected by the excitation. The collection of excited state dipole moments, determined from rotationally resolved Stark spectra helps in the evaluation of various solvent-based methods, which rely on spectral shifts like the Onsager, Lippert-Mataga, or McRae theories.