ESR STUDY OF ORIENTED TRIPLET MOLECULES GENERATED BY EXCITATION WITH POLARIZED LIGHT

Abstract

Abstract— The lowest‐lying triplet states of a variety of aromatic molecules and complexes have been generated by the irradiation of these compounds in solvent glasses with plane‐polarized light. Measurements of the allowed (Δ M=± 1) ESR transitions clearly demonstrate that the triplets so formed are oriented with respect to the external magnetic field. By this method the triplet zero‐field splitting parameters, D and E , can be evaluated simply and reliably. Intramolecular energy transfer is postulated to explain the triplet spectra of Zn( o ‐phen) 2 (NO 3 ) 2 and Zn( o ‐phen) 3 (NO 3 ) 2 . It was observed that in triplet‐triplet energy transfer from benzophenone to naphthalene there is no apparent orientation requirement between the donor and acceptor molecules. Further areas of significance and application of this technique are suggested.