Single-electron transitions and cluster ion super-dissociative recombination

Energy considerations prove that dissociative recombination of the proton-bridge ions, H 2 O.H + .H 2 O and NH 3 .H + .NH 3 , can take place only through single-electron transitions. Any possibility that the recombination coefficients alpha (H 5 O + ) and alpha (H 7 N + ) are large by virtue of the many vibrational modes of the ions is excluded by a comparison with the channel specific dissociative recombination coefficients per equivalent bond for divers polyatomic ions. The nature of a single-electron transition leading to dissociative recombination is described. Approximate calculations show that the rate of the electronic part of the transition can indeed be extremely fast. Dissociative recombination of bigger cluster ions is discussed.