Observation of enhanced rate coefficients in the H${}_2^{+}$ + H${}_2$ $\to$ H${}_3^{+}$ + H reaction at low collision energies

Abstract

The energy dependence of the rate coefficient of the H${}_2^{+}+{\mathrm{H}}_2\to {\mathrm{H}}_3^{+}+\mathrm{H}$ reaction has been measured in the range of collision energies between $k_{\mathrm{B}}\cdot 10$ K and $k_{\mathrm{B}}\cdot 300$ mK. A clear deviation of the rate coefficient from the value expected on the basis of the classical Langevin-capture behavior has been observed at collision energies below $k_{\mathrm{B}}\cdot 1$ K, which is attributed to the joint effects of the ion-quadrupole and Coriolis interactions in collisions involving ortho-H${}_2$ molecules in the $j=1$ rotational level, which make up 75% of the population of the neutral H${}_2$ molecules in the experiments. The experimental results are compared to very recent predictions by Dashevskaya, Litvin, Nikitin and Troe (J. Chem. Phys., in press), with which they are in agreement.

14 pages, 3 figures

References in corpus (3)

• Observation of Quantum Effects in sub Kelvin Cold Reactions
• Dynamics of gas phase Ne${}^{\ast }$ + NH${}_3$ and Ne${}^{\ast }$ + ND${}_3$ Penning ionization at low temperatures
• Quantum Langevin model for exoergic ion-molecule reactions and inelastic processes

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