Black body fragmentation of cationic ammonia clusters

We have carried out a systematic study of the blackbody radiation induced f ragmentation of size-selected ionic ammonia clusters and compared it with t hat of the corresponding hydrates. Specifically, the Ag+ and H+ cation clus ters were studied, with the fragmentation rate constants of the ions solvat ed with ammonia being found to exhibit the same overall linear dependence o n the number of ligands n, which was previously observed for the correspond ing hydrates as well as for a number of other hydrated ions. To facilitate the interpretation of the experimental observations, we have carried out DF T calculations of the cluster structures and of their harmonic: frequencies and intensities. The observed fragmentation rate constants exhibit a satis factory qualitative agreement with the computed rates of energy absorption from the blackbody infrared radiation background.