The Structure of Electronic Excited States: Ultraviolet Excited Raman Spectroscopy and Picosecond Transient Raman Spectroscopy*

We measured the ground and excited state Raman spectra of α,α&s;- 13 C- trans -stilbene. We suggest that the normal modes of vibration in the ground and excited states are significantly mixed. We also measured the ultraviolet excited resonance Raman spectrum and the picosecond transient Raman spectrum of all- trans -diphenylbutadiene. We correlate the increase in the intensity of ground state resonance Raman modes with changes in the band positions in the excited state spectrum. We compare the excited state spectra of trans -stilbene and diphenylbutadiene. We suggest that the excited state of diphenylbutadiene is 1 B u in character.