Formation of H2O+ and H3O+ Cations in Reactions of OH+ and H2O+ with H-2: Experimental Studies of the Reaction Rate Coefficients from T=15 to 300 K
Abstrakt
OH+ and H2O+ cations play a significant role in the chemistry of the cold interstellar medium and hence their hydrogen abstraction reactions with H2 have to be included in ion chemical models. The reactions lead directly or indirectly to H3O+ ions that subsequently recombine with electrons and dissociate into H atoms and H2O.
The experiments described in this paper provide rate coefficients (kOH+ and kH2O+) for the reactions of OH+ and H2O+ with H2 over a wide temperature range (from 15 to 300 K). A cryogenic 22-pole RF ion trap instrument was employed for this purpose.
It was found that kOH+ increases from (0.76 +/- 0.30) x 10-9 cm3 s-1 at 17 K to (1.24 +/- 0.25) x 10-9 cm3 s-1 at 263 K while kH2O+ is nearly constant, varying from (0.93 +/- 0.35) x 10-9 cm3 s-1 at 17 K to (1.00 +/- 0.25) x 10-9 cm3 s-1 at 218 K.