Dissociative recombination of vibrationally relaxed H2O+ ions with electrons has been studied in the heavy-ion storage ring CRYRING. Absolute cross-sections have been measured for collision energies between 0 eV and 30 eV. The energy dependence of the cross-section below 0.1 eV is found to be much steeper than the E-1 behaviour associated with the dominance of the direct recombination mechanism. Resonant structures found at 4 eV and 11 eV have been attributed to the electron capture to Rydberg states converging to electronically excited ionic states. Complete branching fractions for all dissociation channels have been measured at a collision energy of 0 eV. The dissociation process is dominated by three-body H + H + O breakup that occurs with a branching ratio of 0.71.

Faraday Discuss.

Rosén, S, Derkatch, A. M, Semaniak, J, Neau, A, Al Khalili, A, Le Padellec, A, … Larsson, M. (2000). Recombination of simple molecular ions studied in storage ring: dissociative recombination of H2O+. Faraday Discuss., 115, 295–302.