Triplet State Resonance Raman Spectrum of all-trans-diphenylbutadiene

The resonance Raman spectrum of all-trans-diphenylbutadiene (DPB) in its ground state and the resonance Raman spectrum (RRS) of DPB in its short-lived electronically excited triplet state are reported. Transient spectra were obtained by a pump-probe technique using two pulsed lasers. The preresonance spectrum of the ground state is not significantly changed from that of the nonresonance spectrum.

In the resonance spectrum of the triplet state the double-bond stretching mode of the butadiene part is shifted by 43 cm-1 downward to 1582 cm-1 whereas the single-bond stretching mode is essentially unchanged. A transient band at 1556 cm-1 is tentatively assigned to the 8a ring mode shifted downward by 39 cm-1.

These results are discussed in detail.