REACTIONS OF PROTONATED WATER CLUSTERS WITH DEUTERATED AMMONIA - H(H2O)N+ (N = 1-4) + ND3

Reactions of protonated water clusters, H(H2O)n+ (n = 1-4), with deuterated ammonia are studied by using guided ion beam mass spectrometry. Absolute reaction cross-sections are determined as a function of collision energy from thermal energy to over 10 eV. Proton transfer is the only reaction seen for n = 1. For n = 2-4, proton transfer is accompanied by solvent transfer, with the dominant product at low collision energies being HND3 (H2O)n-2+ in each case. At higher collision energies, additional water ligands are lost and the collision-induced dissociation products, H(H2O)x+ where x = 1 to (n - 1), are also observed. The total reaction cross-sections are large and show little dependence on the number of water molecules. The kinetic energy dependence indicates that energy transfer in these reactions is efficient. A mechanism consistent with these results is discussed.