Structure of microcrystals unveiled

A new configuration of the synchrotron at the European Synchrotron Radiation Facility (ESRF) has revealed the structure of microcrystal grains of only one cubic micrometre in size, the team of
French researchers using the facility thus gained a factor of 1,000 on the size of analysable samples.

‘This breakthrough opens up new possibilities of research to chemists, physicists and biologists,’ they say.

The new set-up used by the scientists from the ESRF in Grenoble and the Versailles-based Lavoisier Institute involves a focusing system for the ESRF beam. This is combined with a goniometer,
which allows the sample to be positioned with maximum precision.

The object of interest in this case was an organic-inorganic hybrid compound, a microporous aluminium carboxylate, which could be used for gas absorption or to encapsulate a number of organic
molecules. The crystals – just one cubic micrometre in size – could not have been studied using X-ray or neutron diffraction, because this technique can only be applied to crystals larger than
10 cubic micrometres. Anything smaller than that is considered to be a powder.

While scientists can employ powder diffraction in this case, it is a complicated technique. In addition, the powder diffraction method can only be used on materials with grain sizes of less
than three millionths of a cubic micrometre. Therefore, it has been difficult to determine the structure of newly developed synthetic solids in powder form. Profound knowledge about the
structure of matter is necessary, however, in order to make progress in research, ESRF experts say.

According to Thierry Loiseau from the Lavoisier Institute, this makes this new method a revolution. ‘What was considered a powder in the past has become a crystal today,’ Dr Loiseau explains.
‘Researchers can now bring forward samples left in their cupboards because the sizes had previously prevented their study. Now they will be able to elucidate the structures of theses samples,
with potentially great scientific advances on the horizon.’

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