NSLS-II SEMINAR

Powder Diffraction (PD) is usually believed to be a relatively straightforward method, but continuous progress in X-ray sources and instrumentation (including optics, detectors,…) as well as progress in data analysis and modeling have tremendously broadened the power and the scope of the technique.
PD covers a wide range of topics: structural chemistry, physics, earth science, pharmaceutics, metallurgy, cultural heritage… Materials science is becoming a major area, pushing PD into the study of the structure of (functional, heterogeneous) materials and their defects at the atomic-scale, preferably under their real conditions of synthesis or operation. Using high energy photons, PD can examine the materials in situ or in operando inside a large range of environmental cells, under (extreme) conditions of temperature, pressure, stress, radiation, pH, corrosion, magnetic and electrical fields (parametric experiments). Using intense beams, PD can explore structural transformations, reaction pathways and kinetics in real time (down to the msec scale). Higher momentum transfers in PD open the way to the study of amorphous, partly crystalline or nanocrystalline materials using the direct, model-free Fourier transform of the diffraction data. In the high resolution mode, PD looks at materials of increasing crystallographic complexity (low symmetry, large unit cell), including organics and proteins.
Based on my experience on several SR PD beamlines, and in particular BM16 (now ID31) at the ESRF, I shall show some examples and discuss some possible options for the PD beamline project at NSLS II.