Kinetics of the Reaction D+H2=HD+H

Abstract

The reaction D+H2=HD+H has been studied in the gas phase in the temperature range 274° to 468°K. By attributing the curvature in the Arrhenius plot to quantum-mechanical tunneling and interpreting the results in terms of absolute reaction rate theory the rate constant was given by the expression k3=3.63×1015T−12Γexp(−9.40×103/RT). The results obtained previously for the reaction H+p-H2=o-H2+H fitted the equation k1=1.18×1015T−12Γ exp(−9.21×103/RT). The tunneling factors Γ were calculated on the assumption of a truncated parabolic barrier and gave almost identical values for the force constant of the asymmetric stretching vibration of the complex. The results are compared with recent theoretical calculations.

Zero-point energy, tunnelling, and vibrational adiabaticity in the Mu + H2reaction

“…Agreement between theory and experiment for the D + H 2 thermal rate constants is excellent; when rate constants for the BH-PES are compared [2] to a fit of the low-temperature experimental data [74][75][76], the mean unsigned percent deviation (MUPD) is 6%, and the MUPD between theory and a fit of the high-temperature experimental data of Michael, Su, and Sutherland [77] is 1.5%. The situation is, however, very different for the D + H 2 (v = 1) state-selected rate constants [47], where the QM rate constant on the BH-PES is 63% higher than the experiment.…”

Deuterium chemistry in the primordial gas

“…Thermal rate constants for this reaction have been measured by Ridley, Schulz, & LeRoy (1966), Westenberg & de Haas (1967), Mitchell & LeRoy (1973), and over a wide range of temperatures. Theoretical calculations employing statistical, semiclassical and quantal method have been performed by several groups, and show very good agreement with each other and with the experimental data.…”

H+H2Thermal Reaction: A Convergence of Theory and Experiment

“…There are four previous experimental investigations each for D H 2 [29][30][31][32] and H D 2 [30,[33][34][35]. At high Ts, data for both reactions were obtained by the flash photolysis-shock tube (FPST) technique [32,35] in the T range 700 to 2000 K. The results had a standard deviation (1) of 25% due, in part, to corrections for secondary reaction complications, particularly at Ts above 1400 K. These complications can be eliminated (though the range in T is substantially decreased) by using a thermal source for atoms under such low precursor conditions that secondary reactions are totally negligible.…”

“…It is gratifying to note that the earlier shock tube data overlap the new results within the combined 1 uncertainties of the two sets. The lower-T experimental results [29][30][31]33,34] are also listed in Table I; on experimental grounds suggested in the original references, we have eliminated the lowest-T point from each of three D H 2 studies [29][30][31]. For each reaction, the data summarized by the expressions in Table I were used to evaluate k over the extended T range, 200-2200 K. We have statistically weighted each study equally over its T range.…”