Espectroscopia Raman aplicada a análise mineralógica

Abstract

This work has emerged in response to the lack of comprehensive studies addressing spectroscopic behavior concerning the structural characteristics of a set of minerals involving carbonate and sulfate ions. In this regard, by exploring the potential of the Raman technique, a comprehensive analysis of the spectroscopic properties of crystals has been developed for different mineral samples, varying the conditions for obtaining spectra, with a primary focus on the excitation line. The work is divided into discussions on various results involving the shift, half-width, and relative intensity of Raman bands according to changes in chemical environments for the two predominant anions, either through cationic substitution or alterations in the crystal arrangement. Variations in the Raman spectrum were observed, indicating the influence of the crystal habit of minerals on the relative intensities, along with the interference of the laser spot used in the measurement. The work not only presents scientific contributions through the obtained results but also through the innovative approach in treating and interpreting the collected data. Furthermore, three special chapters enrich the discussion, providing new perspectives on the spectra of rhodochrosite, siderite, azurite, and malachite. For the latter two, considerations are presented regarding possible unconventional resonant Raman effects associated with the intensification of non-totally symmetric modes.