Raman spectroscopy of selected carbonaceous samples

• Published in: International journal of coal geology Vol. 84; no. 3-4; pp. 206 - 212
• Main Authors: Kwiecinska, Barbara, Suárez-Ruiz, Isabel, Paluszkiewicz, Czeslawa, Rodriques, Sandra
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford Elsevier B.V 01.12.2010; Elsevier
• Subjects: Carbonaceous materials; Chemical parameters; Coal; Earth sciences; Earth, ocean, space; Exact sciences and technology; Graphite; High-rank coals; Raman spectroscopy; Reflectance; Sedimentary rocks; Structural order; X-ray diffraction; Structural order; Carbonaceous materials; High-rank coals; Graphite; X-ray diffraction; Raman spectroscopy; Chemical parameters; Reflectance; carbonaceous rocks; Raman spectra; detection; greenschist facies; reflectance; graphitization; graphite; polycyclic aromatic hydrocarbons; heterogeneity; sedimentary rocks; anchimetamorphism; carbon; lattice; coal; rank; anthracite; native elements; granulite facies
• ISSN: 0166-5162; 1872-7840
• DOI: 10.1016/j.coal.2010.08.010

This paper presents the results of Raman spectra measured on carbonaceous materials ranging from greenschist facies to granulite–facies graphite (Anchimetamorphism and Epimetamorphism zones). Raman spectroscopy has come to be regarded as a more appropriate tool than X-ray diffraction for study of highly ordered carbon materials, including chondritic matter, soot, polycyclic aromatic hydrocarbons and evolved coal samples. This work demonstrates the usefulness of the Raman spectroscopy analysis in determining internal crystallographic structure (disordered lattice, heterogeneity). Moreover, this methodology permits the detection of differences within the meta-anthracite rank, semi-graphite and graphite stages for the samples included in this study. In the first order Raman spectra, the bands located near to c.a. 1350cm−1 (defects and disorder mode A1g) and 1580cm−1 (in plane E2g zone—centre mode) contribute to the characterization and determination of the degree of structural evolution and graphitization of the carbonaceous samples. The data from Raman spectroscopy were compared with parameters obtained by means of structural, chemical and optical microscopic analysis carried out on the same carbonaceous samples. The results revealed some positive and significant relationships, although the use of reflectance as a parameter for following the increase in structural order in natural graphitized samples was subject to limitations. ► Raman spectroscopy characterizes the crystallographic structure of carbonaceous materials. ► Raman analysis detects differences within the end-members of the rank scale. ► Reflectance does have limitations, even in the case of highly evolved carbonaceous materials. ► Carbonaceous materials are distinguished according to their degree of graphitization even though their crystallographic properties are very close.