The (NH3)(n) (1){NH3-H-H2O}(+) cluster series produced by Cf-252 fission fragments (FF) impact onto a NH3-H2O 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 {H3O}(+) and {NH4H2O}(+) cores. The theoretical analysis shows that the members of the (NH3)(n) (1){NH4-H2O}(+) series are more stable than those of the (NH3)(n){H3O}(+) series, the (NH3)(2){NH3-H-H2O}(+) structure being the most stable one, in agreement with the experiments. (C) 2009 Elsevier B. V. All rights reserved.