A tool for assisting phase identification by micro‐Raman spectroscopy

Abstract

AbstractAlthough powder X‐ray diffraction is often the primary choice for the analysis of naturally occurring materials, the robust identification of individual components in a complex mixture is usually a challenging task, and other analytical tools are often needed to allow unequivocal phase identification. Among these techniques, the spatial resolution provided by micro‐Raman spectroscopy has proved to be invaluable as a complementary technique to X‐ray diffraction analysis. Accordingly, in this work we present a tool for assisting phase identification by micro‐Raman spectroscopy. This tool was implemented with a graphical user interface, thus facilitating all stages of analysis, including multiple spectra reading, interpolation, and baseline correction, as well as pure component spectra determination by multivariate curve resolution analysis and their identification against an open‐access database. To exemplify the proposed approach, the mineral phases present in an igneous rock from the Serra Geral Formation, Brazil, were identified and then used as the starting point for a full Rietveld refinement of the corresponding X‐ray diffraction pattern. Some phases not identified by micro‐Raman spectroscopy could then be identified by conventional search‐match on the difference X‐ray diffraction pattern. Further testing of the tool yielded the correct identification of the mineral phases used to create noise‐added computer‐generated multiphase Raman spectra. Although the tool developed in this work is currently designed to be used with a database of Raman spectra of minerals, it can be easily modified to be used in a more general context, provided a suitable database of Raman spectra is available.