THE 211 NM EXCITED RESONANCE RAMAN-SPECTRA OF TRANS-STILBENE AND RELATED MOLECULES

We have obtained the 211 nm Raman spectra of trans-stilbene (tS), tran s-stilbene oxide, triphenylethylene, and 4,4'-dimethoxystilbene. We co mpare these spectra with the 211 nm Raman spectra of biphenyl (BP) and 1,4-diphenyl-1,3-butadiene (DPB). In an effort to elucidate the effec t of solvent on the excited state potential energy surface, we calcula te differential Raman cross-sections of the 1630 cm(-1) band of DPB an d the 1610 cm(-1) band of BP at excitation wavelengths of 211 and 746 nm in acetonitrile, ethanol, and cyclohexane. The cross-sections for t hese bands with 746 nm excitation increase with increasing solvent pol arity in the order sigma(cyclohexane) < sigma(ethanol) < sigma(acetoni trile). The trend is different with 211 nm excitation, sigma(acetonitr ile) < sigma(cyclohexane) less than or equal to sigma(ethanol). We att ribute the different trend at 211 nm S-0 microscopic interactions betw een the solvent and the excited state of the solute molecules. We also present a comparison of the 211 nm So resonance Raman spectra and the S-1 resonance Raman spectra of tS and DPB.