PNNL

Abstract

The growth of water clusters in liquid helium results in the formation of cyclic structures up to and including the hexamer. In view of the sequential nature of the molecular pick-up process, the formation of water rings involves the insertion of water monomers into preformed cyclic water clusters. The implication of this observation is that the barriers to the ring insertion process are low enough to be overcome during the experiment. We present a combined experimental and theoretical effort to explore this process in detail. Our results provide important new insights into the dynamics of hydrogen bonded networks. To reconcile the theoretical results with those of the experiments, we have found that the effects of zero point energy are significant in the ring insertion process. In particular, the ring water clusters can be formed by sequential addition of water molecules by surmounting small barriers that are thermally accessible even at the low temperature of the experiment.