The dephasing rate of the three longest lived vibrons of naphthalene-h 8, (T1 ∼ 100 ps) is investigated by picosecond CARS in disordered mixed crystals containing naphthalene-rf s. Vibrational energy transfer can either occur preferentially to one acceptor state or fairly equally to a number of acceptors. For two of the vibrons studied, the decay occurs preferentially to the lower energy d8N vibron of the same normal coordinate. The other vibron studied appears to couple fairly equally to a large number of acceptors since its corresponding d8N vibration is higher in energy and unavailable for decay. The coupling matrix elements are calculated for the specific decay routes and found to be ∼10 greater than the coupling to other acceptor states. For one of the vibrations, nonexponential decays are observed at high d8N concentrations indicating a distribution of environments and hence localization. A fit to a Voight line shape gives an estimate of the inhomogeneous distribution of frequencies experienced by this localized vibration.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry