Time-Resolved Resonance Raman Spectroscopic Investigation of the trans-Stilbene Cation Radical Kinetics in Photolytically Induced Electron-Transfer Reactions

Article abstract of DOI:10.1021/j150655a025

The formation of the trans-stilbene cation radical in photoreactions involving trans-stilbene and the electron-acceptor molecules fumaronitrile, 9-cyanoanthracene, and 9,10-dicyanoanthracene in acetonitrile solution at room temperature is established by the observation of identical transient resonance Raman (TR³) spectra.The excitation profile of the resonance Raman bands closely follows the electronic spectrum of the trans-stilbene radial cation.The decay kinetics of the Raman band intensities measured under various experimental conditions give evidence for two reactions, which are competitive with the homogeneous recombination of the trans-stilbene cation radical with the corresponding radical anion: (i) recombination with a fumaronitrile dimer anion radical and (ii) recombination with superoxide ion to yield oxidation products. trans-Stilbene is one of the first molecules for which the resonance Raman spectra of its short-lived cation and anion radical in the same solvent are now known.In contrast to the electronic absorption spectra, the resonance Raman spectra of the two radical ions are significantly different.