Characterization of a cage form of the water hexamer

Journal article

Water has been studied more extensively than any other liquid, yet its microscopic properties remain poorly understood. The difficulty in obtaining a rigorous molecular-scale description of water structure is largely a consequence of the extended, dynamic hydrogen-bonded network that exists throughout the liquid1. Studies of the structure and dynamics of isolated small clusters of water molecules2-6 provide a means of quantifying the intermolecular forces and hydrogen-bond rearrangements that occur in condensed phases. Experiments2-7 and theory8 strongly suggest that the water trimer, tetramer and pentamer have cyclic minimum energy structures. Larger water clusters are expected8 to have three-dimensional geometries, with the hexamer representing the transition from cyclic to such three-dimensional structures. Here we report investigations by terahertz laser vibration-rotation tunnelling spectroscopy3 of the structure of the water hexamer. A comparison of our results with quantum Monte Carlo simulations of this species suggests that the most stable form of (H2O)6 is indeed a cage-like structure, held together by eight hydrogen bonds (Fig. 1).

Authors: Liu, K; Brown, MG; Carter, C; Saykally, R; Gregory, J

• Publication status: Published
• Journal: NATURE
• Volume: 381
• Issue: 6582
• Pages: 501-503
• Publication date: 1996-06-06
• DOI: 10.1038/381501a0
• ISSN: 0028-0836