title: Temperature-dependent kinetics of charge transfer, hydrogen-atom transfer, and hydrogen-atom expulsion in the reaction of CO+ with CH4 and CD4.
abstract: We have determined the rate constants and branching ratios for the reactions of CO(+) with CH4 and CD4 in a variable-temperature selected ion flow tube. We find that the rate constants are collisional for all temperatures measured (193-700 K for CH4 and 193-500 K for CD4). For the CH4 reaction, three product channels are identified, which include charge transfer (CH4(+) + CO), H-atom transfer (HCO(+) + CH3), and H-atom expulsion (CH3CO(+) + H). H-atom transfer is slightly preferred to charge transfer at low temperature, with the charge-transfer product increasing in contribution as the temperature is increased (H-atom expulsion is a minor product for all temperatures). Analogous products are identified for the CD4 reaction. Density functional calculations on the CO(+) + CH4 reaction were also conducted, revealing that the relative temperature dependences of the charge-transfer and H-atom transfer pathways are consistent with an initial charge transfer followed by proton transfer.
authors.affiliation: Air Force Research Laboratory, Space Vehicles Directorate, Kirtland AFB , New Mexico 87117-5776, United States.
authors.forename: Joshua J
authors.initials: JJ
authors.lastname: Melko
authors.forename: Shaun G
authors.initials: SG
authors.lastname: Ard
authors.forename: Ryan S
authors.initials: RS
authors.lastname: Johnson
authors.forename: Nicholas S
authors.initials: NS
authors.lastname: Shuman
authors.forename: Hua
authors.initials: H
authors.lastname: Guo
authors.forename: Albert A
authors.initials: AA
authors.lastname: Viggiano