A resonance Raman study of solvent effects on the excited state potential surface of trans-stilbene

✍ Scribed by Xiaopei Ci; Anne B. Myers

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 651 KB
• Volume: 158
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(89)87332-4

✦ Synopsis

Raman spectra and absolute Raman cross sections have been mcasurcd for tram-stilbcne in cyclohcxane and methanol using 282 and 266 nm excitation, and calculations have been performed to model the Raman Intensities and absorption spectra. The only out-of-plane vibration observed in either solvent is the hydrogen wag near 960 cm-', which has comparable intensity in both solvents. This suggests that the excited state potential surface for out-of-plane motion in the region near the ground state geometry is similar in polar and nonpolar solvents. The resonance Raman spectrum of trans-stilbene vapor is similar to the solution spectra; in particular, the 5 199 cm-' C=C-4 in-plane bend and its combination bands, intense in low temperature free-jet spectra, are weak at elevated temperatures in both vapor and solution phases. This is probably due to an increase in the effective homogeneous linewidth with increasing temperature. Two weak bands near 950 cm-'. not observed in free-jet emission spectra, appear in the high temperature vapor spectrum. These are tentatively attributed to combination bands of the a, hydrogen out-of-plane wag with the lowest frequency a. phenyl torsion.