Temperature dependence of collisional deactivation of highly vibrationally excited biphenylene

Collisional energy transfer between highly vibrationally excited biphenylene and a variety of mono- and polyatomic bath gases has been measured at temperatures between 333 and 523 K. Biphenylene molecules were initially prepared with an additional vibrational energy of 28 490 cm(-1) by electronic absorption at 351 nm followed by fast internal conversion. The collisional deactivation was observed by detection of the energy dependent UV absorption at the red edge of the strong band at 255 nm. A carefully tested empirical energy calibration, based on high temperature shock tube data was used. A negative temperature dependence of [Delta E], referred to Lennard-Jones collision numbers Z(LJ) was found for the vibrational energies between 10000 and 30000 cm(-1) in all rare gases, N-2, CO2, SF6, ethane, butane and heptane as colliders. This temperature dependence is only very weak in light ran gases and increases systematically with the efficiency of the collider. The absolute values of [Delta E] are analyzed in comparison with recent data sets on related larger polyatomic molecules and with results of trajectory calculations. In the discussion of the measured temperature dependence the problems with a proper distinction between the T-dependence of [Delta E] and of the collision number are also addressed.