Observation of enhanced rate coefficients in the H+2+H2→H+3+H reaction at low collision energies

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Pitt Allmendinger, Johannes Deiglmayr, Katharina Höveler, Otto Schullian, and Frédéric Merkt


The Journal of Chemical Physics 145, 244316

The energy dependence of the rate coefficient of the H2+ + H2 -> H3+ + H reaction has been measured in the range of collision energies between kB * 10 K and kB * 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 kB  1 K, which is attributed to the joint effects of the ion-quadrupole and Coriolis interactions in collisions involving ortho-H2 molecules in the j = 1 rotational level, which make up 75% of the population of the neutral H2 molecules in the experiments. The experimental results are compared to very recent predictions by Dashevskaya et al. [J. Chem. Phys. 145, 244315 (2016)], with which they are in agreement.