Antisymmetric Transition Polarizability Induced by Intermolecular Charge-Transfer Interactions

Abstract

Antisymmetric vibrational transition polarizability induced by intermolecular charge-transfer interactions is proposed and studied by using group theory, especially time-reversal symmetry, and Milliken's theory of charge-transfer complexes. The results show that under the Born−Oppenheimer (B−O) approximation, the antisymmetric transition polarizability of even-electron systems with real represention ground states is zero. But when a donor−acceptor complex is formed by the partial or complete transfer of an electron from donor to acceptor, the acceptor (donor) can have nonzero antisymmetric transition polarizability. Thus charge-transfer-induced antisymmetric light scattering from the interaction even-electron systems, especially charge-transfer complexes, can exist, which is characteristic of charge-transfer interaction and processes. The theoretical results are associated qualitatively with anomalous Raman polarization experiment of anthracene anion−Na+ ion complex and with the complexation enhancements of depolarization ratios of some substituted pyridine−Br2 complexes. The connections of the charge-transfer-induced antisymmetric Raman tensors to sum-frequency vibrational spectroscopy (SFVS) in chiral solutions and in photoionization processes have been discussed.