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Livi, K. J. T., Lafferty, B., Zhu, M., Zhang, S., Gaillot, A.-C. & Sparks, D. L. (2012) Electron Energy-Loss Safe-Dose Limits for Manganese Valence Measurements in Environmentally Relevant Manganese Oxides. Environ. Sci. Technol. 46 970–976.
Added by: Laurent Cournède (2016-03-10 21:28:40) |
| Type de référence: Article DOI: 10.1021/es203516h Numéro d'identification (ISBN etc.): 0013-936X Clé BibTeX: Livi2012 Voir tous les détails bibliographiques  |
Catégories: ID2M Mots-clés: birnessite, EELS, fe, iron, loss spectroscopy, minerals, mn-oxides, oxidation-states, reduction Créateurs: Gaillot, Lafferty, Livi, Sparks, Zhang, Zhu Collection: Environ. Sci. Technol. |
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| Résumé |
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Manganese (Mn) oxides are among the strongest mineral oxidants in the environment and impose significant influence on mobility and bioavailability of redox-active substances, such as arsenic, chromium, and pharmaceutical products, through oxidation processes. Oxidizing potentials of Mn oxides are determined by Mn valence states (2+, 3+, 4+). In this study, the effects of beam damage during electron energy-loss spectroscopy (EELS) in the transmission electron microscope have been investigated to determine the "safe dose" of electrons. Time series analyses determined the safe dose fluence (electrons/nm(2)) for todorokite (10(6) e/nm(2)), acid birnessite (10(5)), triclinic birnessite (10(4)), randomly stacked birnessite (10(3)), and (delta-MnO2 ({<}10(3)) at 200 kV. The results show that meaningful estimates of the mean Mn valence can be acquired by EELS if proper care is taken.
Added by: Laurent Cournède |