![]() ![]() Furthermore, efficient data collection with acquisition times ranging from milliseconds to a few minutes allows one to control the radiation damage of organic compounds and/or perform kinetic studies of structural changes during chemical reactions or under temperature and pressure variations (3). Figure 1 shows the LOD improvement from 0.1% down to 0.01% in weight in an ad-hoc pharmaceutical mixture when the synchrotron optics is fine-tuned. When combining synchrotron-XRPD with the new generation of solid-state, ultra-fast, efficient detectors (4) and unconventional optics set-ups, level of detections (LOD) of the order of 0.01% weight can be obtained even when only micrograms of polycrystalline pharmaceutical powder are available. The photon wavelength can, furthermore, be continuously tuned over a wide range of values, allowing one, for example, to hit or avoid specific absorption edges, or to tailor the absorption by the sample under investigation. In synchrotron-XRPD, x-rays are generated by a synchrotron facility and are at least five orders of magnitude more intense than the best x-ray laboratory source. Synchrotron x-ray powder diffraction (synchrotron-XRPD), which uses a synchrotron x-ray source, offers better data quality than laboratory XRPD for angular resolution, counting statistics, energy tunability, and fast acquisition time (3). It is, however, the quality of an XRPD pattern that defines the accuracy and reliability of the technique, and therefore, the wealth of information that can eventually be extracted (2). In the field of pharmaceutical powders, XRPD is considered the gold standard method for the identification and quantification of solid forms (i.e., polymorphs, solvates, hydrates, salts, co-crystals, amorphous forms) (1). Furthermore, the width and shape of the diffraction peaks unveil further information on the substance microstructure, such as the domain size and shape, strain, and defects. In powder mixtures, XRPD can determine the percentage in weight of the components. The position and relative intensity of the peaks in a powder diffraction pattern (i.e., the Bragg peaks) reflect the chemical composition and the arrangement in space of the atoms of the substance under investigation. ![]() Its power lies in the direct and unique relationship between the powder diffraction pattern of a given substance and its structural order and/or disorder. The 44th crystallographic course at the Ettore Majorana Centre was intended to serve as a complete introduction to the diverse field of powder diffraction, and to provide a firm grounding for attendees, from which to build future research achievements.X-ray powder diffraction (XRPD) is a powerful technique that exploits the interaction between x-rays and matter to study the structural and microstructural properties of materials. #POWDER DIFFRACTION FULL#In the field of data analysis, ingenious algorithms that take full advantage of modern computing power have meant that inorganic, molecular and even protein structures are being solved and refined relatively routinely. Instrumentation at both the laboratory and facility level has become increasingly versatile to the extent that throughput and resolution are no longer mutually exclusive. However, it is perhaps the last decade that has seen some of the most remarkable breakthroughs in experimental powder diffraction and in the analysis of powder diffraction data, to the extent that it is no longer considered to be an analytical technique of last resort. Structural crystallography is often thought to be synonymous with single-crystal crystallography, yet for several decades, powder diffraction has made important contributions to the understanding of materials structure and behaviour. The Power of Powder Diffraction Erice, Italy, 2-12 June 2011 ![]()
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