Lyman-α photodissociation of CH3CFCl2 (HCFC-141b): Quantum yield and translational energy of hydrogen atoms

Abstract

The collision-free, room temperature gas-phase photodissociation dynamics of CH 3 CFCl 2 (HCFC-141b) was studied using Lyman-α laser radiation (121⋅6 nm) by the laser photolysis/laserinduced fluorescence 'pump/probe' technique. Lyman-α radiation was used both to photodissociate the parent molecule and to detect the nascent H atom products via (2p 2 P → 1s 2 S) laser-induced fluorescence. Absolute H atom quantum yield, φ H = (0⋅39 ± 0⋅09) was determined by calibration method in which CH 4 photolysis at 121⋅6 nm was used as a reference source of well-defined H atom concentrations. The line shapes of the measured H atom Doppler profiles indicate a Gaussian velocity distribution suggesting the presence of indirect H atom formation pathways in the Lyman-α photodissociation of CH 3 CFCl 2 . The average kinetic energy of H atoms calculated from Doppler profiles was found to be E T(lab) = (50 ± 3) kJ/mol. The nearly statistical translational energy together with the observed Maxwell-Boltzmann velocity distribution indicates that for CH 3 CFCl 2 the H atom forming dissociation process comes closer to the statistical limit.

Design and construction Optically Gas Laser

“…The laser pulse shape is shown in Fig. ( 6). Many parameters are varied in order to get the optimum conditions for the laser pulse.…”

“…Hirokozn, 1984. The chain reaction, which is initiated by UV flash using F 2 -H 2 mixture, to achieve (14.6) J/Pluse laser output energy at (0.7 atm) [6].In 1986 A.S.Bashkin, utilized the chain reaction for (D 2 -F 2 ) mixture, using flash lamp.In 1996 B.G.Bravy, utilized the chain reaction for F 2 -H 2 mixture, initiated by flash lamp to get 1KJ output laser energy at total pressure of 0.7 atm, with 50 litter. The beam divergence was 10 -4 rad [10].A ClF and H 2 mixture chain reaction, initiated by using XeCl laser (308 nm), 50 J/  laser energy pulse, was utilized by E.B.…”

“…They operate on a rotationalvibrational transition in molecule. This is because many exothermic gas-phase reactions liberate their energy through a stretching vibration in the newly formed bond [6].…”