Shells, silicon & neighbourly atoms

As Andrew Goodwin of Oxford University's Department of Chemistry explains this irregularity is important: it's what allows shells to grow their curved edges and gives silicon its incredibly useful electronic properties. 'Our main technique for establishing what materials look like on the atomic scale is crystallography ,' Andrew tells me, 'and this relies explicitly on the existence of a repeating arrangement of atoms in order to work. So the problem of studying amorphous materials with their seemingly-random arrangements of atoms has remained just that: a problem.' Now, Andrew, and colleagues from Cambridge and Ohio, report in this week's Physical Review Letters how tantalising crystallographic clues could offer a new approach to understanding amorphous materials. 'For decades we've known that the ring-like patterns amorphous materials produce in crystallographic experiments contain limited information about the surrounding environment of each atom,' Andrew comments, 'but the big question has always been how to use this to create a coherent picture of the structure of a material.' 'The spacing of the rings in the 'ring-like pattern' is related to the distances between atoms in the material, and the intensity of the rings is essentially related to how many neighbours each atom has,' Andrew tells me.