Dissociative recombination of the acetaldehyde cation, CH3CHO+

Abstract

The dissociative recombination of the acetaldehyde cation, CH₃CHO⁺, has been investigated at the heavy ion storage ring CRYRING at the Manne Siegbahn Laboratory in Stockholm, Sweden. The dependence of the absolute cross section of the reaction on the relative kinetic energy has been determined and a thermal rate coefficient of k(T) = (1.5 ± 0.2) × 10⁻⁶ (T/300)^{−0.70±0.02} cm³ s⁻¹ has been deduced, which is valid for electron temperatures between ∼10 and 1000 K. The branching fractions of the reaction were studied at ∼0 eV relative kinetic energy and we found that breaking one of the bonds between two of the heavy atoms occurs in 72 ± 2% of the reactions. In the remaining events the three heavy atoms stay in the same product fragment. While the branching fractions are fairly similar to the results from an earlier investigation into the dissociative recombination of the fully deuterated acetaldehyde cation, CD₃CDO⁺, the thermal rate coefficient is somewhat larger for CH₃CHO⁺. Astrochemical implications of the results are discussed.