Recombination Reactions of Atomic Chlorine in Compressed Gases. 2. Geminate and Nongeminate Recombinations and Photolysis Quantum Yields with Argon Pressure Up to 180 bar

Abstract

The laser photolysis/chemiluminescence detection technique was employed to study the recombination reactions of the chlorine atoms generated by photolysis of chlorine molecules with 355 nm laser radiation in compressed Ar gas. The recombination rate constants, the quenching rate constants of the B 3 Π(0 u + ) and A 3 Π(1 u + ) states of the chlorine molecules by argon atoms, and the geminate recombination quantum yields were measured over 10-180 bar argon pressure. The recombination quantum yields were found to vary approximately as the third power of the argon density. For the present weak van der Waals system, the low-pressure asymptotic form of the energy relaxation/diffusion model and a simple molecular collision model were employed to account for the density-dependent behavior over the low-to-medium pressure range. The cage effect in the low-pressure regime and its related theoretical models were discussed.

Recombination Reactions of Atomic Chlorine in Compressed Gases. 3. Molecular Dynamics and Smoluchowski Equation Studies with Argon Pressure up to 6 kbar

“…However, the statistical quantum yield predicts a much larger value, 0.039. Comparing these two values with the experimental result, 0.0050, one could conclude that the adiabatic quantum yield is a better description for the recombination quantum yields at this lower pressure region. Nevertheless, at the high-pressure region, it is expected that the statistical quantum yield would dominate the recombination quantum yields.…”

“…To date, there is only one reported experiment on the measurement of the geminate recombination quantum yields of the chlorine molecules in 25.5−179.3 bar argon pressure at 300 K . The recombination quantum yield at 179.3 bar was measured to be 0.0050.…”

“…The photodissociation/recombination reactions of the molecular halogens in compressed rare gases have received continual attention for more than two decades. − They are generally regarded as model reactions for the study of the photolytic cage effect in the bulk systems. Experimentally, for the earlier studies, the photolysis quantum yields and the nongeminate atomic recombination rate constants of iodine, bromine, and chlorine were measured and the mechanisms for geminate recombination were proposed. − Along this general line, the onset of the geminate recombination reactions of the chlorine molecules in the lower pressure region was investigated recently. , Meanwhile, in another different experimental development, the geminate recombinations of the I 2 /Xe system were intensively studied by the picosecond transient absorption method. , In the past few years, the real-time dynamics of the iodine dissociation/recombination reactions in the rare gas cages over a wide range of gas pressures have been investigated with femtosecond time resolution. − …”

Rate Measurement of the Reaction of CF2Cl Radicals with O2

“…Thus, the net Cl radical concentration should not change due to reaction but should increase due to an accumulation effect between pulses. A possible Cl radical sink could be: with a pressure‐dependent half‐life (1.2–5.8 s in the pressure range of this work), but always greater than the time between pulses (32). Another possible Cl radical sink could be heterogeneous reactions with the cell walls, but these reactions should produce HCl which has not been observed, so that this would be a minor channel.…”

Reaction mechanism of surfactant‐sensitized chemiluminescence of bis(2,4,6‐trichlorophyenyl) oxalate and hydrogen peroxide induced by gold nanoparticles

“…Altering the microenvironment of the CL reaction. The cage structure of the micelle is helpful for stabilizing the excited state and preventing it from quenching, thus the CL quantum yield (Φ CL ) is improved (27,28). The CL quantum yield (Φ CL ) is equal to the product of the excitation quantum yield (Φ EX , excited states per molecule reacted) and the emission quantum yield (Φ EM , photons per excited state).…”