An experimental and theoretical description of the (NH 3) n−1{NH 3–H–H 2O} + cluster ions produced by fast ion bombardment

Abstract

The (NH 3) n −1{NH 3–H–H 2O} + cluster series produced by 252Cf fission fragments (FF) impact onto a NH 3–H 2O ice target have been analyzed theoretically and experimentally. The ion desorption yields show a smooth dependence of the cluster population on its mass, with a relative higher abundance for n = 3. Results of DFT calculations show that two main series of cluster ions may be formed corresponding to the {H 3O} + and {NH 4H 2O} + cores. The theoretical analysis shows that the members of the (NH 3) n −1{NH 4–H 2O} + series are more stable than those of the (NH 3) n {H 3O} + series, the (NH 3) 2{NH 3–H–H 2O} + structure being the most stable one, in agreement with the experiments.