Fe XANES spectra of iron-rich micas

Fe-rich mica crystals have been studied using microbeam XANES spectroscopy of the Fe K edges in order to evaluate the dependence of XANES features and resultant Fe 3+ /σFe values on the orientation of the crystals with respect to the polarization of the synchrotron beam. Polished, thinned samples were prepared with cleavages perpendicular to the plane of their thin sections, and these sections were then rotated relative to the horizontal plane of the ring and the 10 × 15 μm beam. Results show that both pre-edge and main-edge features in these micas exhibit orientation-dependent changes in both peak intensity and energy. These shifts constitute the majority of the error (∼ ± 10%) in determinations of Fe 3+ /σFe by pre-edge energy, a problem that will be overcome in future work through techniques for quantification of grain orientations. Results show distinctive orientation-dependent features in the main edge region, from which it will soon be possible to deconvolute contributions from multiple scattering interactions to obtain information about the electronic properties of micas. Data also demonstrate the exciting potential of XANES pre-edge spectroscopy for routine, in situ analyses of Fe 3+ /σFe on comparable scales to electron microprobe analyses.

[1]  M. Arrio,et al.  High-resolution XANES spectra of iron in minerals and glasses: structural information from the pre-edge region , 2001 .

[2]  M. Benfatto,et al.  MXAN: a new software procedure to perform geometrical fitting of experimental XANES spectra. , 2001, Journal of synchrotron radiation.

[3]  A. Marcelli,et al.  Chromium-containing muscovite: crystal chemistry and XANES spectroscopy , 2001 .

[4]  C. Colliex,et al.  Electron energy-loss spectroscopy of silicate perovskite-magnesiowüstite high-pressure assemblages , 2000 .

[5]  S. Sutton,et al.  Advances in Interpretation of Fe XANES Pre-Edge Spectra, and Resultant Improvements in Microanalysis of Ferric/Ferrous Ratios on Thin Sections , 2000 .

[6]  John H. Jones,et al.  Synchrotron Micro-XANES Measurements of Vanadium Oxidation State in Glasses as a Function of Oxygen Fugacity: Experimental Calibration of Data Relevant to Partition Coefficient Determination , 2000 .

[7]  C. Colliex,et al.  Composition and orientation dependence of the O K and Fe L 2,3 EELS fine structures in Ca 2 (Al x Fe 1-x ) 2 O 5 , 2000 .

[8]  P. Buseck,et al.  Ratios of ferrous to ferric iron from nanometre-sized areas in minerals , 1998, Nature.

[9]  D. Chateigner,et al.  Polarized EXAFS, distance-valence least-squares modeling (DVLS), and quantitative texture analysis approaches to the structural refinement of Garfield nontronite , 1998 .

[10]  S. Bajt,et al.  Redox ratios with relevant resolution: Solving an old problem by using the synchrotron microXANES probe , 1998 .

[11]  E. Ilton,et al.  Quantitative determination of the oxidation state of iron in biotite using x-ray photoelectron spectroscopy: II. In situ analyses , 1997 .

[12]  E. Ilton,et al.  Quantitative determination of the oxidation state of iron in biotite using X-ray photoelectron spectroscopy: I. Calibration , 1997 .

[13]  J. Rehr,et al.  TI K-EDGE XANES STUDIES OF TI COORDINATION AND DISORDER IN OXIDE COMPOUNDS: COMPARISON BETWEEN THEORY AND EXPERIMENT , 1997 .

[14]  K. Hodgson,et al.  A Multiplet Analysis of Fe K-Edge 1s → 3d Pre-Edge Features of Iron Complexes , 1997 .

[15]  A. Marcelli,et al.  Octahedral versus tetrahedral coordination of Al in synthetic micas determined by XANES , 1997 .

[16]  W. Gates,et al.  Surface Structural Model for Ferrihydrite , 1997 .

[17]  G. Schrader,et al.  Temperature dependence of small polaron absorption in biotites , 1996 .

[18]  L. Que,et al.  X-ray Absorption Pre-Edge Studies of High-spin Iron(II) Complexes , 1995 .

[19]  S. Bajt,et al.  X-ray microprobe analysis of iron oxidation states in silicates and oxides using X-ray absorption near edge structure (XANES) , 1994 .

[20]  D. Rancourt.  Mössbauer spectroscopy of minerals , 1994 .

[21]  D. Rancourt,et al.  Determination of accurate (super [4]) Fe (super 3+) , (super [6]) Fe (super 3+) , and (super [6]) Fe (super 2+) site populations in synthetic annite by Moessbauer spectroscopy , 1994 .

[22]  G. Cressey,et al.  Use of L-edge X-ray absorption spectroscopy to characterize multiple valence states of 3d transition metals; a new probe for mineralogical and geochemical research , 1993 .

[23]  D. Rancourt,et al.  Moessbauer absorber thicknesses for accurate site populations in Fe-bearing minerals , 1993 .

[24]  D. Rancourt,et al.  Voigt-based methods for arbitrary-shape static hyperfine parameter distributions in Mössbauer spectroscopy , 1991 .

[25]  A. Manceau,et al.  New Data and a Revised Structural Model for Ferrihydrite: Comment , 1990 .

[26]  G. Waychunas,et al.  Polarized X-ray absorption spectroscopy of metal ions in minerals , 1990 .

[27]  C. Brouder.  Angular dependence of X-ray absorption spectra , 1990 .

[28]  J. Bottero,et al.  Formation of ferric oxides from aqueous solutions: A polyhedral approach by X-ray absorption spectroscdpy: I. Hydrolysis and formation of ferric gels , 1989 .

[29]  S. Titley,et al.  Progressive mixing of isotopic reservoirs during magma genesis at the Sierrita porphyry copper deposit, Arizona: Inverse solutions , 1988 .

[30]  R. Fitzpatrick,et al.  New Data and a Revised Structural Model for Ferrihydrite , 1988 .

[31]  G. Materlik,et al.  On the Multipole Character of the X‐Ray Transitions in the Pre‐Edge Structure of Fe K Absorption Spectra. An Experimental Study , 1988 .

[32]  B. Dutrow,et al.  H content of staurolite as determined by H extraction line and ion microprobe , 1986 .

[33]  M. Dyar,et al.  Mossbauer spectral study of ferruginous one-layer trioctahedral micas , 1986 .

[34]  J. Widom,et al.  X-ray absorption spectroscopy of iron-tyrosinate proteins , 1984 .

[35]  G. Calas,et al.  Coordination of iron in oxide glasses through high-resolution K-edge spectra: Information from the pre-edge , 1983 .

[36]  T. Miyano,et al.  Ferri-annite from the Dales Gorge Member iron-formations, Wittenoom area, Western Australia , 1982 .

[37]  Sebastian Doniach,et al.  Observation of an electric quadrupole transition in the X-ray absorption spectrum of a Cu(II) complex , 1982 .

[38]  W. Goddard,et al.  Ab initio studies of the x-ray absorption edge in copper complexes. I. Atomic Cu 2 + and Cu(ii) Cl 2 , 1980 .

[39]  B. Howes,et al.  Mössbauer and optical spectra of biotite: A case for Fe2+−Fe3+ Interactions , 1980 .

[40]  P. Eisenberger,et al.  Observations and interpretation of x-ray absorption edges in iron compounds and proteins. , 1976, Proceedings of the National Academy of Sciences of the United States of America.

[41]  W. N. Sharp,et al.  The Pikes Peak batholith, Colorado front range, and a model for the origin of the gabbro—anorthosite—syenite—potassic granite suite , 1975 .

[42]  James R. Brown,et al.  A Mössbauer study of coexisting hornblendes and biotites: quantitative Fe3+/Fe2+ ratios , 1975 .

[43]  Rosenr M. HezeN,et al.  The Crystal Structures of One-Layer Phlogopite and Annite , 1973 .

[44]  F. Dodge.  Chlorites from granitic rocks of the central Sierra Nevada batholith, California , 1969, Mineralogical Magazine.

[45]  A. Marcelli,et al.  X-Ray Absorption Spectroscopy of the Micas , 2002 .

[46]  D. Chateigner,et al.  Oxidation-reduction mechanism of iron in dioctahedral smectites: I. Crystal chemistry of oxidized reference nontronites , 2000 .

[47]  S. Lauterbach,et al.  Mössbauer and ELNES spectroscopy of (Mg,Fe)(Si,Al)O3 perovskite: a highly oxidised component of the lower mantle , 2000 .

[48]  D. Chateigner,et al.  Oxidation-reduction mechanism of iron in dioctahedral smectites: II. Crystal chemistry of reduced Garfield nontronite , 2000 .

[49]  P. V. van Aken,et al.  Microanalysis of Fe3+/ΣFe in oxide and silicate minerals by investigation of electron energy-loss near-edge structures (ELNES) at the Fe M2,3 edge , 1999 .

[50]  P. V. van Aken,et al.  Quantitative determination of iron oxidation states in minerals using Fe L2,3-edge electron energy-loss near-edge structure spectroscopy , 1998 .

[51]  Gordon E. Brown,et al.  X-ray absorption spectroscopy; applications in mineralogy and geochemistry , 1988 .

[52]  M. Apted,et al.  X-ray K-edge absorption spectra of Fe minerals and model compounds: Near-edge structure , 1983 .