The ultrafast IR-Raman technique is used to compare picosecond timescale vibrational energy relaxation (VR) of a polyatomic liquid, acetonitrile (CH3CN), following excitation of either a C-H stretching fundamental (~3000 cm-1) or a pair of vibrations at about the same energy, the CN stretch and C-C stretch. When the vibrational pair is excited via combination band pumping, the CN stretch lifetime decreases by more than an order of magnitude, and an oscillation is observed in the C-C stretch population. These studies of a pair of interacting vibrations on the same molecule provide insight into the complex behavior expected from vibrationally excited nascent products of chemical reactions of condensed-phase polyatomic molecules.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry