'Tunneling' State Of Water Molecule Discovered
An interesting state of the water molecule, using neutron scattering and computational modelling has been discovered by a team of scientists at the Department of Energy's Oak Ridge National Laboratory (ORNL). It is a unique behavior that has not been observed in any known gas, liquid or solid states.
The "unique tunneling state of the molecule" is limited to hexagonal ultra-small channels of just one mineral, beryl. The study shows unique features of water under extreme confinement in rocks, soil and cell walls. This is a useful finding, explains the team.
"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 new finding can help scientists to become better aware of the thermodynamic properties of water in closed environments, such as in carbon nanotubes and at mineral interfaces in diverse 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 tunnelling behaviour of water is discovered, showing that the molecules get delocalized around a ring, which makes it look rather like a top.
"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.