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Р. Шекли

on 20 October 2015. Posted in О воде

Electrical detection of orthopara conversion in fullerene-encapsulated water*

Benno Meier, Salvatore Mamone, Maria Concistre, Javier Alonso-Valdesueiro1, Andrea Krachmalnicoff, Richard J. Whitby & Malcolm H. Levitt pdf

School of Chemistry, University of Southampton, Southampton SO17 1BJ, UK

Water exists in two spin isomers, ortho and para, that have different nuclear spin states. In bulk water, rapid proton exchange and hindered molecular rotation obscure the direct observation of two spin isomers. The supramolecular endofullerene H2O@C60 provides freely rotating, isolated water molecules even at cryogenic temperatures. Here we show that the bulk dielectric constant of this substance depends on the ortho/para ratio, and changes slowly in time after a sudden temperature jump, due to nuclear spin conversion. The attribution of the effect to orthopara conversion is validated by comparison with nuclear magnetic resonance and quantum theory. The change in dielectric constant is consistent with an electric dipole moment of 0.51±0.05 Debye for an encapsulated water molecule, indicating the partial shielding of the water dipole by the encapsulating cage. The dependence of bulk dielectric constant on nuclear spin isomer composition appears to be a previously unreported physical phenomenon.

*NATURE COMMUNICATIONS | 6:8112 | DOI: 10.1038/ncomms9112


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