# Synopsis: Deuterium outruns hydrogen in diffusion race

Heavier molecular deuterium diffuses through a nanoporous molecular sieve faster than molecular hydrogen.

Separation by molecular sieving in narrow windows of microporous and nanoporous materials consisting of cagelike frameworks of atoms is normally governed by the relative sizes of the diffusing molecules. However, for isotopes, such molecular sieving is precluded from a classical viewpoint as they are of similar size and shape.

In 2005, Anil Kumar and Suresh Bhatia from the University of Queensland, Australia, used atomistic molecular dynamics simulations to study the diffusion of ${\text{D}}_{2}$ and ${\text{H}}_{2}$ in a microporous material. They predicted that transport diffusivities would be reduced by quantum interactions, and that ${\text{D}}_{2}$ would diffuse significantly faster than ${\text{H}}_{2}$ in quantum confined systems at low temperatures [1]. Now, in a paper appearing in Physical Review Letters, Than Nguyen and Suresh Bhatia from the University of Queensland, and Hervé Jobic from the Université Lyon, France, use quasielastic neutron scattering to observe this reverse kinetic molecular sieving at a microscopic level for temperatures below $100\phantom{\rule{0.333em}{0ex}}\text{K}$.

With the development of optimal sieving materials, the process may be used to separate light isotopes, including ${\text{H}}_{2}$ and ${\text{D}}_{2}$. – Jane Throwe

[1] A.V. Anil Kumar and Suresh K. Bhatia, Phys. Rev. Lett. 95, 245901 (2005).

More Features »

### Announcements

More Announcements »

## Subject Areas

Materials Science

## Previous Synopsis

Interdisciplinary Physics

## Next Synopsis

Atomic and Molecular Physics

## Related Articles

Materials Science

### Synopsis: Golden Mystery Solved

A long-standing discrepancy between experiments and theory concerning the electronic properties of gold has now been resolved. Read More »

Materials Science

### Synopsis: Metamaterial Inverts the Hall Effect

A metamaterial that looks like chainmail has a Hall coefficient whose sign is flipped compared to the material it’s made from. Read More »

Mechanics

### Focus: Why Some Gels Shrink under Stress

The gel material that helps blood clot in a wound has anomalous material properties because of the interaction between the gel's fluid and its microscopic fiber network, according to experiments. Read More »