Functional PXRD analysis

Among the techniques that probe the average or long-range structure, powder X-ray diffraction (PXRD) and neutron diffraction (ND) will be briefly discussed. Techniques that provide local, atomistic information that will be mentioned are nuclear magnetic resonance (NMR) spectroscopy. X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and pair distribution function (PDF) analysis. A brief introduction to the underlying theory of each technique will be provided along with relevant examples to illustrate the type of information that can be... 

The inherent specificity and quantitative power towards the crystalline state make pXRD as the technique of choice for studying crystallization from amorphous systems (Ochsenbein and Schenk 2006). Also, the instrumental flexibility allows in situ monitoring of crystallization as function of time, temperature, pressure, RH, or combinations. An API can crystallize to different polymorphs from ASD (Guns et al. 2011). The reference powder pattern enables the identification/quantification of the polymorphs developing in ASD (Ivanisevic et al. 2010). Preferred orientation of crystalline faces is a major source of error. Generally, analysis in transmission mode reduces the preferred orientation and avoid other instrumentally induced distortions and anisotropic shifts (Moore et al. 2009). 

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