学术报告通知
题目：Where do powder diffraction and microdiffraction meet?
报告人：Dr. Catherine Dejoie
The European Synchrotron Radiation Facility (ESRF), Grenoble, France
时间：2016年1月 17日（周日），早上9点-11点
地点：材料学院215会议室
摘要： Structural characterization of polycrystalline materials is usually performed using powder diffraction techniques, and indeed over the last two decades these methods have developed to the point that quite complex structures can be solved and refined in an almost routine manner. However, in some difficult cases, the powder condition cannot be achieved, therefore alternative methods have to be devised. Two examples related to the structure analysis of polycrystalline materials will be presented. In the first example, the structure of the indigo@silicalite pigment, an analog of ancient Maya Blue was determined by combining X-ray Laue microdiffraction and powder diffraction techniques. Laue microdiffraction was used to map the unit cell changes (and thereby the indigo distribution) within a single crystal and to retrieve the most probable space group. With this information, the indigo@silicalite structure could be solved and refined from the powder diffraction data. In my second example, I will present an alternative method for studying polycrystalline materials developed in collaboration with the Swiss Free-electron Laser Project. Using a non-monochromatic beam (4% energy bandpass), the reflection intensities of stationary crystals can be measured reliably. If a unique diffraction pattern of many randomly oriented crystals can be recorded and processed, a complete analysis of the crystal structure will be possible from a single snapshot. Potential applications for in situ time-resolved studies will be discussed.
报告人简介:
Dr. Catherine Dejoie is a Beamline Scientist at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. She received her Ph.D degree in Condensed Matter and Light Scattering at the Institut Néel, Grenoble University, France, in 2009. She worked as an ALS postdoctoral fellow at the Advanced Light Source (ALS) of Lawrence Berkeley National Laboratory, before joining the Laboratory of Crystallography at ETH Zurich, Switzerland in 2012. Her current interests include the development of X-ray diffraction techniques, both at synchrotron and free-electron laser facilities, and the application of such techniques to the structural study of complex small molecules and inorganic materials.