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

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