Discovery Could Reveal How Water Behaves in Rocks on Earth

When water is trapped inside a tiny channel, it behaves like no other solid, liquid or gas. That's according to a study at the National Laboratory which looked at what happens when water occupies tiny space in minerals. In their latest experiment, scientists studied water trapped in a beryl — a mineral found in emeralds Photo: emerald green gypsum var selenite crystals cluster

• Scientists studied water trapped in a beryl, a mineral found in emeralds
• New state of water behaves like no other solid, liquid or gas
• At low temperatures, water trapped in hexagons shows quantum behavior

When water is trapped inside a tiny channel, it behaves like no other solid, liquid or gas.

That's according to a new study at the Department of Energy's Oak Ridge National Laboratory which looked at what happens when water occupies tiny spaces in minerals.

In their latest experiment, scientists studied water trapped in a beryl — a mineral found in emeralds. The mineral contains hexagonal ultra-small channels, which are 5 angstrom across.

An angstrom is 1/10-billionth of a meter, and individual atoms are typically about 1 angstrom in diameter. When water enters this tiny space, it's known as tunneling, and scientists found it causes it to behave in strange ways.
'At low temperatures, this tunneling water exhibits quantum motion through the separating potential walls, which is forbidden in the classical world,' said lead author Alexander Kolesnikov of ORNL's Chemical and Engineering Materials Division.

'This means that the oxygen and hydrogen atoms of the water molecule are 'delocalised' 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 discovery was made possible with the Spallation Neutron Source, an accelerator-based neutron source facility that provides the most intense pulsed neutron beams in the world.

Neutron scattering allows scientists to count scattered neutrons, measure their energies and the angles at which they scatter, and map their final positions. This information can reveal the molecular structure and behaviour of materials.

The existence of the tunneling state of water should help scientists better describe the properties and behaviour of water in highly confined environments.

This could include water diffusion and transport in the channels of cell membranes, in carbon nanotubes and at minerals throughout Earth.  'This discovery represents a new fundamental understanding of the behaviour of water and the way water utilizes energy,' said ORNL co-author Lawrence Anovitz.

'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.'

While previous studies have observed tunneling of atomic hydrogen in other systems, the ORNL discovery that water exhibits such tunneling behaviour is unprecedented.



The study was published in the journal Natural Sciences