Identification and valuation of paramagnetic radicals in natural dolomites as an indicator of geological events |
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| Authors: | R W A Franco F Pelegrini A M Rossi |
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| Institution: | (1) Instituto de Física, Universidade Federal de Goiás, 74001-970, CP: 131, Goiania, GO, Brazil E-mail: robertofrancobr@hotmail.com, BR;(2) Centro Brasileiro de Pesquisas Físicas, Rua Xavier Sigaud 150, 22290-180, Rio de Janeiro, RJ, Brazil, BR |
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| Abstract: | Geological sedimentary dolomite samples from the Superior Proterozoic are studied using electron paramagnetic resonance (EPR)
spectroscopy. The complex spectra in the g=2.0 region is composed of Mn2+ lines and signals due to crystallization and radiation-induced defects. Measurements in microwave frequencies of 9.5 GHz
(X-band) and 35 GHz (Q-band), and thermal and/or radiation treatments allowed identification of seven paramagnetic radicals
in the g=2.0 region: (1) isotropic organic radical; (2) axial SO2
−; (3) axial PO2
0 or PO2
2−; (4) isotropic CO2
−; (5) axial CO2
−; (6) axial CO3
3−; (7) isotropic unknown line. The use of these paramagnetic centres as indicators of geological events is discussed.
Received: 18 March 2002 / Accepted: 3 October 2002 |
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| Keywords: | Dolomite EPR Gamma radiation Defects |
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