A team of researchers from the Department of Energy's Oak Ridge National Laboratory (ORNL) has discovered a new state of the water molecule using neutron scattering and computational modeling. The molecule's unique behavior has not been observed in any known gas, liquid or solid states.
The unique tunneling state of the molecule is confined in hexagonal ultra-small channels of the mineral beryl. The findings reveal unique features of water under ultra confinement in rocks, soil and cells walls, and the team believes that the results will be beneficial to many disciplines.
"At low temperatures, this tunneling water exhibits quantum motion through the separating potential walls, which is forbidden in the classical world," said Alexander Kolesnikov of ORNL's Chemical and Engineering Materials Division and lead author of the study. "This means that the oxygen and hydrogen atoms of the water molecule are 'delocalized' and therefore simultaneously present in all six symmetrically equivalent positions in the channel at the same time. It's one of those phenomena that only occur in quantum mechanics and has no parallel in our everyday experience."
The tunneling state of water discovered in the study could help scientists better understand the thermodynamic properties of water in confined environments, such as in carbon nanotubes and at mineral interfaces in various geological environments.
"This discovery represents a new fundamental understanding of the behavior of water and the way water utilizes energy," ORNL co-author Lawrence Anovitz said. "It's also interesting to think that those water molecules in your aquamarine or emerald ring - blue and green varieties of beryl - are undergoing the same quantum tunneling we've seen in our experiments."
The discovery is unprecedented for its demonstration of water exhibiting tunneling behavior, revealing that in this state, water molecules are delocalized around a ring, causing it to take a strange top-like shape.
"The average kinetic energy of the water protons directly obtained from the neutron experiment is a measure of their motion at almost absolute zero temperature and is about 30 percent less than it is in bulk liquid or solid water," Kolesnikov said. "This is in complete disagreement with accepted models based on the energies of its vibrational modes."
The findings were published in the April 22 issue of Physical Review Letters.
