RESONANCE RAMAN-STUDY OF A 2-CHROMOPHORE SYSTEM - THE 2 1-COMPLEX OF HEXAMETHYLBENZENE WITH TETRACYANOETHYLENE/

Raman excitation profiles are presented for the 2:1 electron donor-acc eptor (EDA) complex of hexamethylbenzene (HMB) and tetracyanoethylene (TCNE) in cyclohexane. Though the absorption and Raman spectra of the 1:1 and 2:1 complexes are similar, distinct differences are found in t he Raman excitation profiles (REPs) of vibrational modes common to bot h systems. REPs of the 2:1 complex show intensity cancellation that is taken as evidence for interference of two charge-transfer excited sta tes. The implications of the observed spectra concerning excited state electron delocalization are considered. (C) 1997 Elsevier Science B.V .