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Ian Robinson - London Centre for Nanotechnology

Materials investigation by Bragg Coherent X-ray Diffraction


Coherent X-ray Diffraction is a method of imaging materials on the nanometre length scale using the high coherent flux of the latest synchrotron sources. Diffraction signals can be used to image and identify specific parts of the sample under investigation. When Bragg peaks of the sample are used, the resulting image becomes highly sensitive to the presence of strain, so the method is effective in exploring structural changes in materials. Bragg Coherent Diffraction Imaging (BCDI) can be used with XFEL sources from which the X-rays are highly coherent, but also in very short pulses. These can be used to “freeze” vibrations in materials and observe new transient phenomena. This also opens an opportunity to discover new phases of matter during the transients between more stable states.

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Bio sketch

Ian Robinson’s research interest is X-ray diffraction using synchrotron radiation (SR). During 11 years at Bell Labs, he developed the methods for studying surface structure using X-ray diffraction. These methods, based on crystal truncation rods, have become the definitive technique for the determination of the atomic positions at surfaces and interfaces. These surface methods are still used today at the major SR facilities, NSLS (Brookhaven), ESRF (Grenoble), APS(Chicago) and SLS (Villigen). He was awarded two prizes for the surface structure work, the Warren Prize in 2000 and the Surface Structure Prize in 2011.

To develop these methodology of X-ray diffraction with SR, he built two beamlines. The first was a dedicated surfaces and interface structure beamline X16A at the National Synchrotron Light Source (Brookhaven). The second was 34-ID for coherent diffraction at the Advanced Phoyon Source(Chicago). More recently he has been developing methods of using the very high coherence of the latest SR sources to enable direct 3D imaging of structure. This is potentially useful for examining strain distributions inside complex materials on the nanometre length scale. He was awarded the 2015 Gregori Aminoff prize by the Swedish Academy of Sciences.

Robinson is currently following three major grant-supported research directions. The first, entitled "nanosculpture", looks at strains induced in nanometre-sized crystals either synthesised from atoms in a ’bottom up’ procedure, or else carved by lithography from bulk materials in a ’top down’ approach. The second is to study the structure of the human chromosome by X-ray imaging methods. The third is to develop new X-ray imaging methods based on deliberate modulation of the phase by suitably developed X-ray optics.

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