New multivariate methods to monitor structural dynamics by X-ray diffraction
Structural changes occurring in solid-state reactions can be revealed by X-ray diffraction through in situ experiments, where an external perturbation is applied on the sample during measurements. The advent of new generation X-ray sources and detectors allows fast measurements and enables time-resolved investigations. A large number of diffraction profiles is collected in few minutes, which has to be analyzed individually by using long computational procedures, requiring heavy user intervention. A collaboration between the Institute of Crystallography of Bari (group of Dr. Caliandro), the University of Piemonte Orientale of Alessandria (group of Prof. Milanesio) and the Polytechnic of Bari (Dr. Guccione) has led to the development of new algorithms based on multivariate analysis, which are able to process in a fast and automatic way all diffraction profiles taken together. They correct diffraction peak disalignments due to crystal lattice distortions, extract relevant information from the dataset, and detect active atoms, i.e. those responding to the external perturbation, out of the bulk material.
The algorithms have been implemented in the computer program RootProf, distributed by the Institute of Crystallography. The results have been published in Physical Chemistry Chemical Physics, a prestigious journal of the Royal Society of Chemistry, and have been selected for the back cover of its current issue.