title: Dissociative recombination of HCl+, H2Cl+, DCl+, and D2Cl+in a flowing afterglow.
abstract: Dissociative recombination of electrons with HCl+, H2Cl+, DCl+, and D2Cl+has been measured under thermal conditions at 300, 400, and 500 K using a flowing afterglow-Langmuir probe apparatus. Measurements for HCl+and DCl+employed the variable electron and neutral density attachment mass spectrometry (VENDAMS) method, while those for H2Cl+and D2Cl+employed both VENDAMS and the more traditional technique of monitoring electron density as a function of reaction time. At 300 K, HCl+and H2Cl+recombine with kDR= 7.7±2.14.5× 10-8cm3s-1and 2.6 ± 0.8 × 10-7cm3s-1, respectively, whereas D2Cl+is roughly half as fast as H2Cl+with kDR= 1.1 ± 0.3 × 10-7cm3s-1(2σ confidence intervals). DCl+recombines with a rate coefficient below the approximate detection limit of the method (≲5 × 10-8cm3s-1) at all temperatures. Relatively slow dissociative recombination rates have been speculated to be responsible for the large HCl+and H2Cl+abundances in interstellar clouds compared to current astrochemical models, but our results imply that the discrepancy must originate elsewhere.
authors.affiliation: Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117, USA.
authors.forename: Justin P
authors.initials: JP
authors.lastname: Wiens
authors.affiliation: Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117, USA.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Miller
authors.affiliation: Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117, USA.
authors.forename: Nicholas S
authors.initials: NS
authors.lastname: Shuman
authors.affiliation: Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117, USA.
authors.forename: Albert A
authors.initials: AA
authors.lastname: Viggiano