Vibrationally Excited Populations from IR-Multiphoton Absorption. 3. Energy Transfer between 1,1,2-Trifluoroethane and Argon

摘要

Infrared multiphoton absorption at several laser fluences (1079.85/cm) has been used to generate vibrationally excited 1,1,2-trifluorethane molecules at energies below the reaction threshold. A technique is demonstrated in which collisional deactivation of the vibrationally excited molecules by argon was monitored with time-resolved infrared fluorescence from the C-H stretch modes. The experimental results were simulated by using a full collisional master equation treatment that incorporated Quack's theory of multiphoton absorption, as parameterized elsewhere for TFE, and a calibration curve relating fluorescence to vibrational energy (previously determined for TFE). When the exponential model for collision transition probabilities was used, the simulations gave sub d = (200 + or - 20) + (0.005 + or - 0.002)E where is the energy step size (cm-1) for deactivating collisions by argon and E is the vibrational energy of the excited TFE. The simulations showed that sub d has a significant energy dependence, but it does not exhibit a detectable temperature dependence over the range from about 400 to 1000 K. In the Introduction, current research activities by several workers active in the area of large molecule energy transfer are briefly surveyed. Keywords: Laser induced chemistry; Infrared; Multiphoton; Master equation; Reactive yields; Excited populations; Reprints.