Measurements of the diffusion coefficients of atomic chlorine in rare gases

Abstract

The technique for measuring the diffusion coefficients of reactive atomic species through their radiative recombination reactions is applied to multicomponent mediums. A series of diffusion coefficients of chlorine atoms in chlorine molecules mixed with rare gases M(He, Ne, Ar, Kr, and Xe) were measured for various Cl2 and M mole fractions. By extrapolating to zero molecular chlorine pressure, the diffusion coefficients of chlorine atoms in rare gases were obtained. The measured values of the diffusion constant are DCl–He =0.75±0.12, DCl–Ne =0.32±0.05, DCl–Ar =0.19±0.03, DCl–Kr =0.14±0.02, and DCl–Xe =0.12±0.02 cm2/s, respectively, at 296 K and 1 atm rare gas pressure. The corresponding hard sphere collision diameter of chlorine atoms in rare gases was calculated and a comparison was made between the diffusion coefficients of Cl–rare gas and Ar–rare gas systems at 296 K.

The direct observation of secondary radical chain chemistry in the heterogeneous reaction of chlorine atoms with submicron squalane droplets

“…24,25 Here the gas phase diffusion coefficient of Cl g in Ar (D Cl-Ar = 0.19 cm 2 s À1 ) is used for the correction instead of Cl g in nitrogen, which to our knowledge has not been measured. 26,27 Recently, very good agreement between measured and calculated diffusion coefficients for OH radicals were published, 28 and by using the same formula we obtained the same value of diffusion coefficient (0.19 cm 2 s À1 ) for Cl g in N 2 . The effective uptake coefficient at 20% O 2 , corrected for the gas phase diffusion, is g Sq Cl = 0.65 AE 0.07.…”

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

“…The kinetic models for the geminate and nongeminate recombination reactions of the photodissociated chlorine atoms under argon pressure are analyzed separately in this section. The simplest but yet quite general photodissociation and recombination mechanism for chlorine molecules, which is consistent with the present experimental study, may be written as [37][38][39][40] in which M is a third body which may include all the chemical species in the system, Cl 2 * and Cl 2 represent the radiative and nonradiative electronic states of the chlorine molecules, respectively, k r and k n are the corresponding recombination rate constants, is the rate constant of photon emission, is the rate constant of the third-body quenching reaction, and eq 1 represents the photodissociation and the simultaneous hot-atom thermalization processes.…”

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

“…The Ar−Ar interaction potential is represented by the Lennard-Jones 6−12 potential with parameters ε Ar - Ar = 83.3 cm -1 and σ Ar - Ar = 3.41 Å . For the Cl−Ar potential, it has been recognized that the interaction potentials of the halogen-atom/rare-gas systems are close to those of the corresponding rare-gas/rare-gas systems as suggested in the molecular beam scattering experiments. , The similarity of the transport properties between the Cl/Ar and Ar/Ar systems also supports that the Cl−Ar potential could be well-approximated by the above Ar−Ar potential . In this study, the Ar−Ar potential form was adapted directly for the Cl−Ar potential.…”

“…31,32 The similarity of the transport properties between the Cl/Ar and Ar/Ar systems also supports that the Cl-Ar potential could be well-approximated by the above Ar-Ar potential. 33 In this study, the Ar-Ar potential form was adapted directly for the Cl-Ar potential. The Ar-Cl 2 potential was then calculated by the atom-atom additivity model.…”