Laue diffraction: The key to neutron crystallography from submillimetric-volume single crystals

Abstract

For several decades, chemists and physicists have been fascinated by molecular compounds rich in delocalized electrons. In the solid state these compounds may offer a very rich fan of properties: optical, conduction and dielectric, magnetic... Each state is the result of a delicate balance amongst intra- and/or intermolecular interactions which can be controlled, not just by direct chemical substitution, but also by external parameters such as temperature, pressure, continuous electric or magnetic fields, or by light. The recent evolution of this field of science towards more and more sophisticated materials makes also more and more difficult their crystal growth. While neutron scattering is an extremely powerful technique to get precise structural information, it is also often disregarded in this field because usually large single crystals are required. With the recent renaissance of Laue techniques using the very intense flux provided by the reactor of the Institut Laue-Langevin (ILL), accurate structural and/or magnetic information can be now extracted routinely from molecular crystals of volume 0.1 mm 3 or smaller, with easy possibilities of high pressure (up to 3 GPa) down to 0.2 K. A general survey of these new possibilities is illustrated by an example taken from the field of low-dimensional organic complexes.