Реферат: High pressures can influence the structure of different materials leading to a number of interesting phenomena like phase transitions, changes in conductivity, amorphisation, metallisation etc. Pressures can also be used for chemical synthesis and often lead to formation of previously unknown solvates and clathrates. In order to understand all these phenomena one needs to know exact structure changes caused by high pressures. X-ray diffraction with diamond anvil cells (DACs) is widely used to determine crystal structures for most organic, inorganic and biological crystalline samples. The quality of diffraction data is critically important for obtaining reliable information on atomic coordinates and intermolecular distances. The recent improvements in high-pressure X-ray diffraction were related not only to technical aspects of diffraction experiment (new DAC designs, fast and sensitive detectors, brilliant X-ray sources), but also to development of a new software for sample centering, absorption correction, recognizing and excluding unwanted reflections that do not belong to the sample, data reduction, finding the orientation matrices for several crystallites in the same diamond anvil cell. The recent developments in instrumentation and software allowed even determination of electron charge density distribution for such a samples. All types of high-pressure studies require rigorous experimental planning and special methods of X‑ray diffraction data treatment since the crystal is not “free” but located in confined environment in hydrostatic liquid inside DAC with certain construction with limited opening windows for X-ray probe. A lot of questions can arise on planning the experiment: which pressure transmitting media to choose? how fast the pressure should be increased? Is not it better to perform all the experiments at synchrotron rather than at lab source if I have this opportunity? which factors should be taken into account on data collection and reduction? This list of issues is quite far from being complete. The aim of my contribution is to give a brief overview of the most interesting and useful generally arising questions and try to answer them. I would also like to highlight the importance of considering some “hidden” factors like choice of pressure transmitting media, pressure variation protocol and diffraction equipment while planning and performing the diffraction measurements to obtain the most reliable results of high-pressure experiment. Author acknowledges the support by the Ministry of Science and Higher Education of Russia; the work was carried out jointly by Boreskov Institute of Catalysis (project AAAA-A21-121011390011-4) and Novosibirsk State University. The work was done using the equipment of Research and Education Centre “Molecular Design and Ecologically Safe Technologies” at NSU.

Библиографическая ссылка: Zakharov B.A.
High-Pressure X-ray Diffraction Experiments and Data Reduction: The Difference from Ambient Pressure Studies and Factors Influencing the Data Quality
International Workshop on Chemical Crystallography and Structural Biology “The Third Struchkov Meeting” 15-19 Nov 2021