Isotope Effects in the Vibrational Deactivation of Large Molecules.

BEATRIZ M. TOSELLI; JOHN R. BARKER

AMER INST PHYSICS

Año: 1992 p. 1809 - 1809

Collisional deactivation of highly vibrationally excited gas phase toluene-d, and benzene-d,pumped at 248 nm, has been investigated by monitoring the time resolved infraredfluorescence from the C-D stretch modes near 4.3 ,um. For toluene-d, , energy transfer datawere obtained for about 20 collider gases, including unexcited toluene-d, ; for benzene-d,, onlya few colliders were investigated. For both systems the data were analyzed by an inversiontechnique that converts the fluorescence decay to the bulk average energy, from which iscalculated the average energy transferred per collision, ((AE ))i,, . Data obtained earlier forbenzene-d,, were reanalyzed and the revised results are reported. Results for both normal anddeuterated excited species show ((AE ))inv to be nearly directly proportional to the vibrationalenergy (W))inV of the excited molecule from 5 000 to 25 000 cm - ?. However, for puretoluene-d, , benzene-d,, and a f