title: Dissociative recombination of protonated methanol.
abstract: The branching ratios of the different reaction pathways and the overall rate coefficients of the dissociative recombination reactions of CH3OH2+ and CD3OD2+ have been measured at the CRYRING storage ring located in Stockholm, Sweden. Analysis of the data yielded the result that formation of methanol or deuterated methanol accounted for only 3 and 6% of the total rate in CH3OH2+ and CD3OD2+, respectively. Dissociative recombination of both isotopomeres mainly involves fragmentation of the C-O bond, the major process being the three-body break-up forming CH3, OH and H (CD3, OD and D). The overall cross sections are best fitted by sigma = 1.2 +/- 0.1 x 10(-15) E(-1.15 +/- 0.02) cm2 and sigma = 9.6 +/- 0.9 x 10(-16) E(-1.20 +/- 0.02) cm2 for CH3OH2+ and CD3OD2+, respectively. From these values thermal reaction rate coefficients of k(T) = 8.9 +/- 0.9 x 10(-7) (T/300)(-0.59 +/- 0.02) cm3 s(-1) (CH3OH2+) and k(T) = 9.1 +/- 0.9 x 10(-7) (T/300)(-0.63 +/- 0.02) cm3 s(-1) (CD3OD2+) can be calculated. A non-negligible formation of interstellar methanol by the previously proposed mechanism via radiative association of CH3+ and H2O and subsequent dissociative recombination of the resulting CH3OH2+ ion to yield methanol and hydrogen atoms is therefore very unlikely.
authors.affiliation: Molecular Physics Division, Department of Physics, Stockholm, Sweden. wgeppert@physto.se
authors.forename: W D
authors.initials: WD
authors.lastname: Geppert
authors.forename: M
authors.initials: M
authors.lastname: Hamberg
authors.forename: R D
authors.initials: RD
authors.lastname: Thomas
authors.forename: F
authors.initials: F
authors.lastname: Osterdahl
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authors.initials: F
authors.lastname: Hellberg
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authors.lastname: Zhaunerchyk
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authors.initials: A
authors.lastname: Ehlerding
authors.forename: T J
authors.initials: TJ
authors.lastname: Millar
authors.forename: H
authors.initials: H
authors.lastname: Roberts
authors.forename: J
authors.initials: J
authors.lastname: Semaniak
authors.forename: M
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authors.lastname: af Ugglas
authors.forename: A
authors.initials: A
authors.lastname: Källberg
authors.forename: A
authors.initials: A
authors.lastname: Simonsson
authors.forename: M
authors.initials: M
authors.lastname: Kaminska
authors.forename: M
authors.initials: M
authors.lastname: Larsson