Shock-Tube Measurement of Dissociation Rates of Hydrogen

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Abstract
The rate of dissociation of hydrogen was measured in a shock tube by following the absorption of ultraviolet light by the H21Πu—1Σg+ Werner transition. Dissociation was observed in mixtures of from 1.00 to 30.1% hydrogen over the temperature range from 2950° to 5330°K. A digital computer program was used to calculate reaction profiles behind a normal shock wave for arbitrary reaction rate coefficients assuming that the reaction proceeded by the mechanism H2+M⇄ lim krkd2H+M,where the third body, M, may be Ar, H2, or H. By varying the reaction rate coefficients, it was possible to match the computed reaction profiles with the observed profiles for all experiments; however, the temperature range covered was not sufficiently wide to permit an accurate determination of the temperature dependence of kr. Consequently, a T−1 dependence was arbitrarily chosen. The recombination rate coefficients in cm6 mole−2 sec−1 were 7.5×1017 T−1 for argon as the third body, 7.5×1018 T−1 for H2, and 5×1019 T−1 for H, where T is in °K.