title: Low-Temperature Reactivity of C2n+1N(-) Anions with Polar Molecules.
abstract: Following the recent discovery of molecular anions in the interstellar medium, we report on the kinetics of proton transfer reactions between cyanopolyynide anions C2n+1N(-) (n = 0, 1, 2) and formic acid HCOOH. The results, obtained from room temperature down to 36 K by means of uniform supersonic flows, show a surprisingly weak temperature dependence of the CN(-) reaction rate, in contrast with longer chain anions. The CN(-) + HCOOH reaction is further studied theoretically via a reduced dimensional quantum model that highlights a tendency of the reaction probability to decrease with temperature, in agreement with experimental data but at the opposite of conventional long-range capture theories. In return, comparing HCOOH to HC3N as target molecules suggests that dipole-dipole interactions must play an active role in overcoming this limiting effect at low temperatures. This work provides new fundamental insights on prototypical reactions between polar anions and polar molecules along with critical data for astrochemical modeling.
authors.affiliation: Institut de Physique de Rennes, Département de Physique Moléculaire, UMR CNRS 6251, Université de Rennes 1 , Campus de Beaulieu, 35042 Rennes Cedex, France.
authors.forename: Baptiste
authors.initials: B
authors.lastname: Joalland
authors.affiliation: Institut de Physique de Rennes, Département de Physique Moléculaire, UMR CNRS 6251, Université de Rennes 1 , Campus de Beaulieu, 35042 Rennes Cedex, France.
authors.forename: Nour
authors.initials: N
authors.lastname: Jamal-Eddine
authors.affiliation: Department of Chemistry and Biochemistry, University of Maryland , College Park, Maryland 20742-2021, United States.
authors.forename: Jacek
authors.initials: J
authors.lastname: Kłos
authors.affiliation: Laboratoire Ondes et Milieux Complexes, UMR CNRS 6294, Université du Havre , 25 rue Philippe Lebon, BP 1123, 76063 Le Havre Cedex, France.
authors.forename: François
authors.initials: F
authors.lastname: Lique
authors.affiliation: Institut des Sciences Chimiques de Rennes, Ecole Nationale Supérieure de Chimie de Rennes, UMR CNRS 6226, 11 Allée de Beaulieu, 35708 Rennes Cedex 7, France.
authors.forename: Yann
authors.initials: Y
authors.lastname: Trolez
authors.affiliation: Institut des Sciences Chimiques de Rennes, Ecole Nationale Supérieure de Chimie de Rennes, UMR CNRS 6226, 11 Allée de Beaulieu, 35708 Rennes Cedex 7, France.
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Guillemin
authors.affiliation: Institut de Physique de Rennes, Département de Physique Moléculaire, UMR CNRS 6251, Université de Rennes 1 , Campus de Beaulieu, 35042 Rennes Cedex, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Carles
authors.affiliation: Institut de Physique de Rennes, Département de Physique Moléculaire, UMR CNRS 6251, Université de Rennes 1 , Campus de Beaulieu, 35042 Rennes Cedex, France.
authors.forename: Ludovic
authors.initials: L
authors.lastname: Biennier