Hydrogen Chloride Vibrational Populations Produced by the H and D Atom Reactions with SCl2 and S2Cl2

Abstract

Infrared emission intensities from HCl and DCl products in high vibrational levels have been used to measure energy partitioning in the reactions of H and D atoms with SCl2 and S2Cl2. The results are compared to the infrared chemiluminescence from the H and D atom reactions with Cl2. The relative vibrational level populations were measured under experimental conditions such that vibrational relaxation was minimized. The H atom reactions with SCl2 and S2Cl2 partitioned >37% and >36% of the available energy into vibrational energy of the hydrogen chloride product. Within our experimental error the fraction of energy partitioned to vibration was the same for the H and D atom reactions. In the reactions of H and D with SCl2 and S2Cl2 the distribution of rate constants for formation of HCl† and DCl† into the vibrational levels apparently peaks at levels intermediate between υ = 0 and the maximum possible level of vibrational excitation. The distributions are similar to those from the H and D atom reactions with Cl2. The additional internal degrees of freedom in S2Cl2 relative to SCl2 did not greatly affect the partitioning of energy to the HCl† product.

Infrared Chemiluminescence Studies of the Reactions H + S2Cl2, H + SOCl2 and H + SCl2

“…One can see from N,=z/N'=l that our vibrational distribution (Table 2) is less relaxed than the distribution of Setser and coworkers [3J evaluated using the measured relaxation technique. Setser and his collaborators also attempted to correct for relaxation effects in their "comparative technique" using the known relaxation behaviour of HCl formed by the reaction H + Clz' This procedure is doubtful because of the different deactivation probabilities for Cl, and SzCl z [3,14].…”

“…Early measured relaxation studies by Johnson et al [3] showed the presence of excited HCI molecules. The first rotational distribution for this reaction was reported by Heydtmann and Polanyi [4].…”

“…The evaluated relative vibrational distribution is compared with the results obtained in other laboratories [3,4] in Table 2. The population obtained by the measured relaxation technique reported by Johnson et al [3] seems to be more relaxed than the other distributions considering N v= 1 and N v= 2' The arrested relaxation measurements are preferable. Our data are in reasonable agreement with the results of Heydtmann and Polanyi obtained in apparatus I but the distribution favoured by the authors (apparatus II) is not in good agreement with our new data.…”