HIGH-RESOLUTION XANES SPECTRA OF IRON IN MINERALS AND GLASSES: STRUCTURAL INFORMATION FROM THE PRE-EDGE REGION
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dc.contributor.author | Galoisy L. | |
dc.contributor.author | Calas G. | |
dc.contributor.author | Arrio M.A. | |
dc.date.accessioned | 2021-02-12T04:02:46Z | |
dc.date.available | 2021-02-12T04:02:46Z | |
dc.date.issued | 2001 | |
dc.identifier | https://www.elibrary.ru/item.asp?id=596900 | |
dc.identifier.citation | Chemical Geology, 2001, 174, 1-3, 307-319 | |
dc.identifier.issn | 0009-2541 | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/24745 | |
dc.description.abstract | High-resolution X-ray Absorption Near-Edge Structure (XANES) spectra of iron allow to take into account the effects of the coordination numbers on the quantification of redox values. Volcanic glasses show split pre-edge features, arising from a bimodal distribution between the relative contributions of ferric and ferrous iron. The chemical shift between these two oxidation states, 2 eV, has been resolved using a 400 Si monochromator. High-resolution pre-edge spectroscopy shows the distribution of ferric and ferrous iron between various coordination states. Ferrous iron is mostly fivefold-coordinated and minority fourfold-coordinated while ferric iron occurs in fourfold and sixfold-coordinated sites. The importance of 6Fe3+ in basaltic glasses may explain the formation of magnetite during glass oxidation. The increase of 4Fe3+ in the more silicic, pantelleritic glass is consistent with the peralkaline character of this glass. The increase of the proportion of tetrahedral Fe3+, accompanied by more covalent Fe3+-O bonds, is consistent with the chemical dependence of redox equilibria in magmatic systems, in which the most differentiated terms correspond to more oxidizing compositions. | |
dc.subject | VOLCANIC GLASS | |
dc.subject | X-RAY SPECTROSCOPY | |
dc.subject | REDOX | |
dc.subject | COORDINATION | |
dc.subject | IRON | |
dc.title | HIGH-RESOLUTION XANES SPECTRA OF IRON IN MINERALS AND GLASSES: STRUCTURAL INFORMATION FROM THE PRE-EDGE REGION | |
dc.type | Статья |
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