NANOSECOND TIME-RESOLVED RESONANCE RAMAN INVESTIGATION OF THE T-1 -] T-N TRANSITION OF 2-BROMONAPHTHALENE

We have obtained nanosecond time-resolved resonance Raman spectra of t he T-1 --> T-n transition of 2-bromonaphthalene in methanol solvent. T he transient resonance Raman spectra indicate that there are mostly st ructural changes in the C-C stretch nu(5a) vibrational coordinate alon g with a smaller amount of change in the C-Br stretch and C-Br in plan e deformation coordinates. This suggests that the T-1 --> T-n transiti on of 2-bromonaphthalene does not initially excite a directly dissocia tive triplet state and a predissociative mechanism is probably respons ible for the efficient T-n state C-Br bond cleavage found in previous photochemistry studies. (C) 1998 Elsevier Science B.V. All rights rese rved.