N. Fay et K. Luther, Temperature dependence of collisional deactivation of highly vibrationallyexcited biphenylene, Z PHYS CHEM, 214, 2000, pp. 839-864
Citations number
61
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
ZEITSCHRIFT FUR PHYSIKALISCHE CHEMIE-INTERNATIONAL JOURNAL OF RESEARCH IN PHYSICAL CHEMISTRY & CHEMICAL PHYSICS
Collisional energy transfer between highly vibrationally excited biphenylen
e and a variety of mono- and polyatomic bath gases has been measured at tem
peratures between 333 and 523 K. Biphenylene molecules were initially prepa
red with an additional vibrational energy of 28 490 cm(-1) by electronic ab
sorption at 351 nm followed by fast internal conversion. The collisional de
activation 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 n
egative temperature dependence of [Delta E], referred to Lennard-Jones coll
ision numbers Z(LJ) was found for the vibrational energies between 10000 an
d 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 g
ases and increases systematically with the efficiency of the collider. The
absolute values of [Delta E] are analyzed in comparison with recent data se
ts on related larger polyatomic molecules and with results of trajectory ca
lculations. In the discussion of the measured temperature dependence the pr
oblems with a proper distinction between the T-dependence of [Delta E] and
of the collision number are also addressed.