Coherent X-ray diffraction reveals real space 3D structures of nanocrystals

The appearance of the ultimate X-ray microscope, with atomic-scale resolution and capable of seeing deep inside objects, has long been awaited. Professor I. Robinson (University College London, UK) and his team recently made a significant step towards realizing this dream, using the technique of coherent X-ray diffraction imaging, the possibility of which was first pointed out by Sayre (Acta Crystallogr. 5, 843 (1952)) but not demonstrated until 1999 by Miao et al (Nature 400, 342 (1999)). They observed the growth of nanometer-sized Pb crystals inside the vacuum chamber. The results showed that asymmetries in the diffraction pattern can be mapped to deformities, providing a detailed 3-D map of their location in the crystal. This new method shows that the interior structure of atomic displacements within single nanocrystals can be obtained by direct inversion of the diffraction pattern. The technique is an attractive alternative to electron microscopy because of the superior penetration of materials of interest by the electromagnetic waves, which are often less damaging to the sample than electrons. The experiments were done at beamline 34-ID-C at the Advanced Photon Source (APS) in the United States. For more information, see the paper, "Three-dimensional mapping of a deformation field inside a nanocrystal", Mark A. Pfeifer et al., Nature 442, 63 (2006).