how to change molecular structure of water?
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Is the structure of water asymmetric? We may be asking the wrong question if we don't consider over what timescale
A controversy about the structure of liquid water that has raged for almost a decade may be laid to rest by a new computational study. Thomas Kühneand Rustam Khaliullin of the University of Mainz in Germany say that both sides of the argument may be right, depending on how you investigate the question.1
The tetrahedral coordination of water molecules – each one hydrogen-bonded to four neighbours – has an almost iconic status in studies of water structure. That’s certainly how it appears in ice, and both experiments and simulations seemed to suggest that the liquid state has this same motif in its dynamic, less ordered hydrogen-bonded network. But that picture was challenged in 2004 by measurements of water’s x-ray absorption spectrum (XAS) made by Anders Nilsson of Stanford University and co-workers.2 They argued that their results showed water molecules bound primarily into linear chains and rings.
This claim was strongly disputed – some argued that Nilsson and colleagues had made unwarranted assumptions in deriving a structure from their raw data.3 The Stanford team has since modified their picture to propose that water contains a mixture of near-tetrahedral bonds and highly distorted hydrogen bonds with little directionality.4