Reactive collisions between O− and H2 have been studied experimentally at temperatures ranging

from 10 K to 300 K using a cryogenic radiofrequency 22-pole ion trap. The rate coefficients for

associative detachment, leading to H2O + e−, increase with decreasing temperature and reach a flat

maximum of 1.8 × 10−9 cm3 s−1 at temperatures between 20 K and 80 K. There, the overall reaction

probability is in good agreement with a capture model indicating efficient non-adiabatic couplings

between the entrance potential energy surfaces. Classical trajectory calculations on newly calculated

potential energy surfaces as well as the topology of the conical intersection seam leading to the

neutral surface corroborate this. The formation of OH− + H via hydrogen transfer, although occurring

with a probability of a few percent only (about 5 × 10−11 cm3 s−1 at temperatures 10–300 K),

indicates that there are reaction paths, where electron detachment is avoided.

from 10 K to 300 K using a cryogenic radiofrequency 22-pole ion trap. The rate coefficients for

associative detachment, leading to H2O + e−, increase with decreasing temperature and reach a flat

maximum of 1.8 × 10−9 cm3 s−1 at temperatures between 20 K and 80 K. There, the overall reaction

probability is in good agreement with a capture model indicating efficient non-adiabatic couplings

between the entrance potential energy surfaces. Classical trajectory calculations on newly calculated

potential energy surfaces as well as the topology of the conical intersection seam leading to the

neutral surface corroborate this. The formation of OH− + H via hydrogen transfer, although occurring

with a probability of a few percent only (about 5 × 10−11 cm3 s−1 at temperatures 10–300 K),

indicates that there are reaction paths, where electron detachment is avoided.

typ: | article |
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journal: | Journal of Chemical Physics |

volume: | 142 |

pages: | 014304 |

year: | 2015 |