Observation of enhanced rate coefficients in the H2+ + H2 → H3+ + H reaction at low collision energies

The energy dependence of the rate coefficient of the H-2(+) + H-2 -> H-3(+) + H reaction has been measured in the range of collision energies between k(B) . 10 K and k(B) . 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(B) . 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 et al. [J. Chem. Phys. 145, 244315 (2016)], with which they are in agreement. Published by AIP Publishing.