Temperature dependence of vibrational energy transfer between vibrationally excited polyatomic molecules and bath gases

Efficiency of vibrational energy transfer (VET) in vibrational quasicontinuum of triplet states was estimated from the dependence of time-resolved delayed fluorescence of benzophenone and anthraquinone on bath gas pressure. The negative temperature dependence for vibration–vibration (V–V) and positive for vibration–translation (V–T) energy transfers from benzophenone and anthraquinone to bath gases (C2H4, SF6, CCl4, C5H12) were obtained between 373 and 553 K. Polarizability and dipole moment of colliding molecules seem to affect the efficiency of V–V relaxation. These data reflect the dominance of long-range attractive interactions in V–V energy transfer and short-range repulsive interactions in V–T energy transfer.