Intermolecular and Intramolecular Excited State Charge Transfer

A primary mechanism of energy relaxation and chemical change inorganic molecules in excited electronic states is charge transfer. 1 Thecharge transfer process can be intermolecular, involving an excitedmolecule and a neighboring molecule, one serving as an acceptor andthe other as a donor molecule, or intramolecular, involving a chargeredistribution in the excited molecule which produces a very largeexcited state dipole moment. In our investigations of the dynamics of these various charge transferprocesses, a picosecond laser pulse was used to excite the moleculesof interest. The charge transfer dynamics were monitored by a varietyof techniques, including transient absorption of the excited chargetransfer complex (exciplex) or ion radicals by a time delayedpicosecond pulse, and fluorescence from the exciplex and from theinitially excited molecule using a picosecond streak camera fordetection.