Nanosecond time-resolved resonance Raman investigation of the T1→Tn transition of 2-bromonaphthalene

We have obtained nanosecond time-resolved resonance Raman spectra of the T1→Tn transition of 2-bromonaphthalene in methanol solvent. The transient resonance Raman spectra indicate that there are mostly structural changes in the C–C stretch ν5a vibrational coordinate along with a smaller amount of change in the C–Br stretch and C–Br in plane deformation coordinates. This suggests that the T1→Tn transition of 2-bromonaphthalene does not initially excite a directly dissociative triplet state and a predissociative mechanism is probably responsible for the efficient Tn state C–Br bond cleavage found in previous photochemistry studies.