title: Electron and ion reactions with hexamethyldisiloxane and pentamethyldisiloxane.
abstract: The dissociative recombination of electrons with the hexamethyldisiloxane (HMDSO) cation ((CH(3))(3)Si-O-Si(CH(3))(3))(+) and the pentamethyldisiloxane cation ((CH(3))(3)Si-O-Si(CH(2))(2))(+) as well as the ion-molecule reaction between Ar(+) and HMDSO have been studied at 300 K using a flowing afterglow Langmuir probe-mass spectrometer apparatus. The rate constants for these reactions, measured directly for the first time, are, respectively, alpha(1)=1.8 x 10(-6), alpha(2)=3.6 x 10(-6) cm(3)s, and k=2.0 x 10(-9) cm(3)s with uncertainties of +/-30%. In addition, the electronic attachment to neutral HMDSO was also studied and an upper limit value of the rate constant was determined to be beta=3.3 x 10(-11) cm(3)s.
authors.affiliation: Laboratoire Physique des Atomes, Lasers, Molécules et Surfaces, Equipe: Astrochimie Experimentale, UMR CNRS-Université No. 6627 Bâtiment 11 C, Campus de Beaulieu, Université de RENNES I, 35042 Rennes Cedex, France.
authors.forename: S
authors.initials: S
authors.lastname: Carles
authors.forename: J L
authors.initials: JL
authors.lastname: Le Garrec
authors.forename: J B A
authors.initials: JB
authors.lastname: Mitchell