Podrobnosti záznamu

Název
    Oxidation state and coordination of Fe in minerals: An Fe K-XANES spectroscopic study
Údaj o odpovědnosti
    Max Wilke, Francois Farges, Pierre-Emmanuel Petit, Gordon E. Brown jr., Francois Martin
Autor
    Brown, Gordon E., jr.
    Farges, Francois
    Martin, Francois
    Petit, Pierre-Emmanuel
    Wilke, Max
Jazyk
    anglicky
Zdrojový dokument - seriál
    American mineralogist
Svazek/č.
    Vol. 86, no. 5-6
Strany
    p. 714-730
Rok
    2001
Poznámky
    8 obr., 4 tab., 3 s.bibl.
    il.
    Ronsberg (či Ronšperk) je starší název Poběžovic-významné naleziště hercynitu
    Zkr. název ser.: Amer. Mineralogist
Předmětová skupina
    Eh hodnota
    koordinace
    krystalochemie
    oxidace
    oxidy
    silikáty
    spektrometrie absorbční
    synchron
    uspořádanost atomů
    železo
Geografické jméno
    Brazílie
    ČR-Čechy
    Francie
    Madagaskar
    Mexiko
    Poběžovice (Domažlice)
    Rusko-Ural
    USA
Klíčové slovo
    Coordination
    Fe
    K-XANES
    Minerals
    Oxidation
    Spectroscopic
    State
    Study
Abstrakt (anglicky)
   High-resolution Fe K-edge XANES spectra of a series of crystalline Fe2+ and Fe3+ -bearing model compounds were measured in an effort to correlate characteristics of the pre-edge feature with oxidation state and local coordination environment of Fe atoms. The model compounds comprise 30 natural minerals and synthetic compounds, with Fe coordination environments ranging from 4 to 12 O atoms for Fe2+, including 5-coordinated trigonal bipyramidal Fe2+, and from 4 to 6 O atoms for Fe3+. Most pre-edge spectra show two components (due to crystal field splitting) that are located just above the Fermi level. The most useful characteristics of the Fe-K pre-edge for determining Fe oxidation state and coordination number are the position of its centroid and its integrated intensity. The separation between the average pre-edge centroid positions for Fe2+ and Fe3+ is 1.4˝0.1 eV.
   Thus, the position of the pre-edge feature can be used as a measure of the average Fe-redox state, with the average pre-edge position for mixed Fe2+-Fe3+ compounds occurring between positions for Fe2+ and Fe3+. The lowest pre-edge normalized heights and intergrated intensities are observed for the most centrosymmetric sites of Fe, in agreement with previous studies (see Waychunas et al. 1983). Examination of the pre-edge features of mechanical mixtures of phases containing different proportions of Fe2+ and Fe3+ suggests that the pre-edge position and intensity for these mixtures can vary quite non-linearly with the average redox state of Fe
Přispěvatel
    Česká geologická služba
Kód přispěvatele
    ČGS (UNM)
Zdrojový formát
    U
Datum vložení
    21. 8. 2007
Datum importu
    8. 8. 2012