Crystallographic Data Diffracting Techniques

Without a doubt, one of the most important uses of XRPD in pharmaceuticals is derived from application as the primary determinant of polymorphic or solvatomorphic identity [34], Since these effects are due to purely crystallographic phenomena, it is self-evident that x-ray diffraction techniques would represent the primary method of determination. Owing to its ease of data acquisition, XRPD is particularly... 

The crystallographic data for these phases, including tables of calculated d-spacings and intensities for X-ray powder diffraction patterns, have been collected in Chapter 13. Characterization by electron microscopy, a particularly important technique because of the nature of the materials, is reviewed in Chapters 14 and IS. 

Simulated annealing A structure determination from diffraction data involves the development of an initial model, that is a structure solution step, and then completion and refinement of the model. Why are these steps distinct The answer is that today s structure refinement technology can operate effectively only when the starting model is relatively dose to the actual model crystallographic least squares techniques are unable to locate global... 

Ex situ macroscopic properties of adsorbates and interphases not sensitive towards a transfer of the sample from the electrochemical cell into an analysis system (in most cases a UHV chamber) can be studied with additional techniques. The crystallographic data can be derived from low energy electron diffraction (LEED) [72] this is possible only if the sample has a minimum degree of ordering. 

For all these reasons, it is compulsory to begin to establish the basis of a reliable crystallographic approach, so as to get a reasonable material characterization. Then, among the various characterization techniques, a choice can be made. Both diffracting techniques (x-rays and electrons) and imaging techniques (transmission electron microscopy) are well adapted, becanse they exploit the same data, and they must be discussed in some detail. 

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