The dissociative recombination of protonated acrylonitrile, CH2CHCNH+, with implications for the nitrile chemistry in dark molecular clouds and the upper atmosphere of titan

Abstract

Measurements on the dissociative recombination (DR) of protonated acrylonitrile, CH2CHCNH+, have been performed at the heavy ion storage ring CRYRING located in the Manne Siegbahn Laboratory in Stockholm, Sweden. It has been found that at ∼2meV relative kinetic energy about 50% of the DR events involve only ruptures of X-H bonds (where X=CorN)while the rest leads to the production of a pair of fragments each containing two heavy atoms (alongside H and/or H2). The absolute DR cross section has been investigated for relative kinetic energies ranging from ∼1 meV to 1 eV. The thermal rate coefficient has been determined to follow the expression k(T) = 1.78 × 10-6 (T/300)-0.80 cm3 s-1 for electron temperatures ranging from ∼10 to 1000 K. Gas-phase models of the nitrile chemistry in the dark molecular cloud TMC-1 have been run and results are compared with observations. Also, implications of the present results for the nitrile chemistry of Titan's upper atmosphere are discussed.