Measurements and simulations of rate coefficients for the deuterated forms of the H2+ + H2 and H3+ + H2 reactive systems at low temperature

The rate coefficients of various isotopic variations of the H-2(+) + H-2 and H-3(+) + H-2 reactions in the 10-250 K temperature range were measured using a cryogenic 22 pole radio frequency ion trap. The processes involving diatomic ions were found to behave close to the Langevin rate, whereas temperature-dependent rate coefficients were obtained for the four isotopic exchange processes with triatomic ions. Fitting the experimental data using a chemical code allowed us in specific cases to constrain rate coefficients that were not directly measured in the ion trap. The reported rate coefficients suggest a more efficient hydrogenation of deuterated H-3(+) forms than usually assumed in astrochemical models, which might affect deuteration rates in warmer environments.