The assignments of many of the vacuum ultraviolet valence and Rydberg states of trans-1,3-butadiene are investigated using resonance Raman spectroscopy which provides data on distortions and vibronic activity. The 1Bg(π-3s) Rydberg state (50 144 cm-1) is confirmed to be vibronically coupled to the 1 1 Bu(π π*) valence state by modes of au symmetry, especially V 12 (CH2 twist). The higher energy Rydberg states were also examined and an analysis was made of both their assignments and their behavior when resonantly enhanced. Selective excitation into the sharp vibrational structure of these Rydberg states provides a striking example of mode specific resonance enhancement. Evidence was sought for the location of the high energy 1Ag (ππ*) state, said to be near 60 000 cm-1, but the results were indefinite.
ASJC Scopus subject areas
- General Physics and Astronomy
- Physical and Theoretical Chemistry