Merged beam measurement of the dissociative recombination of HCN⁺and HNC⁺

Abstract

Cross sections for the dissociative recombination of isomeric HCN+/HNC+ ions with electrons were measured using the single-pass merged beam experiment located at the University of Western Ontario in Canada. The source conditions were varied so that an HCN+/HNC+ mixture was first studied. The HNC+ ion was then isolated via the fast ion-molecule reaction HCN++CO2HNC++CO2. The two sets of measurements, which both refer to vibrationally (and electronically) excited states of HCN+ and HNC+, exhibit differences in the magnitudes of the cross sections. Thermal rate coefficients have been calculated for both species. An attempt has been made to identify the valence states involved in the dissociation to the CN+H channel for HCN+ recombination.

Dissociative recombination of N2+, O2+, and NO+: Rate coefficients for ground state and vibrationally excited ions

“…[17] Interestingly, for the first time, the differences between the direct and indirect processes (HCN + /HNC + isomers) have now been observed experimentally [Sheehan et al, 1999;Talbi et al, 2000]. The direct process has been found to be the considerably more efficient of the two, with a rate coefficient nearly 30 times larger than that for the indirect process in this instance.…”

Titan's ion chemistry: A laboratory perspective

“…It was also observed that the products of dissociation lead to extensive fragmentation of the ion. The dissociative recombination reactions of HCN þ and HCNH þ have also been examined using a single pass merged beam method (Sheehan et al, 1999) and for HCNH þ the storage ring method was also used (Semaniak et al, 2001). HCN and HNC were found to make up 67% of all recombination products from recombination of HCNH þ .…”

Commission 14: Atomic and Molecular Data: (Donnees Atomiques Et Moleculaires)

“…The process of dissociative recombination is an important process in which the electron is captured by a molecular ion resulting in a number of neutral products. It is an efficient process producing complex neutral molecules: H^ (Larson et al 2000, Serov et al 2001, Pichl, Nakamura, k Horacek 2001, HD+ (Amitay et al 1999, Larson et al 2000, Orel 2000, Larson k Orel 2001, IL+ (Jensen et al 2001, Glosfk et al 2001, Strasser et al 2001a, H 2 0+ (Jensen et al 1999), H 3 0+ (Neau et al 2000, Bahati et al 2001c), HCN+ (Sheehan et al 1999, Talbi, LePadellec, k Mitchell 2000, HeJ (Carata, Orel, k Suzor-Weiner 1999), HeH+ (Larson k Orel 1999), LiH+ (Krohn et al 2001), CH+ (Carata et al 2000), C2H+ (Derkatch et al 1999), OH+ (Larson et al 2000), O j (Peverall et al 2001), and NO+ (Mostefaoui et al 1999, Schneider et al 2000, LePadellec et al 2001.…”