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X-ray near edge absorption spectroscopy was used to probe the electronic structure of multiferroic orthorhombic LuMnO3 polycrystalline samples and strained, twin-free orthorhombic (1-10) LuMnO3 films grown by pulsed laser deposition on (1-10) YAlO3 substrates. For all o-LuMnO3 samples x-ray near edge absorption spectroscopy spectra reveal that the pre-edge structure is influenced by the increase in MnO6 distortion as a result of the smaller Re-ion or film strain. Furthermore there is clear evidence of anisotropic Mn-O bonding and Mn orbital ordering along the c- and [110] direction. The experimental film and bulk data are in agreement with ab initio simulations. [ABSTRACT FROM AUTHOR]

Abstract: We report results from an extensive study on the speciation of zinc (Zn) and its relation to the mobility and bioavailablity of this element in a smelter contaminated soil and an in situ remediated area of this soil 12 yr after the application of cyclonic ash and compost. Emphasis was placed on the role of neoformed precipitates in controlling Zn speciation, mobility and bioavailability under different environmental conditions. Twelve years after remediation, the pH of the treated and non-treated soil differed by only 0.5 pH unit. Using state-of-the-art electron and X-ray microscopies in combination with micro-focused extended X-ray absorption fine structure (μ-EXAFS) spectroscopy, no major differences in Zn speciation were found between samples of the treated and non-treated soil. In both soils, 30% to 50% of Zn was present in smelter related minerals (willemite, hemimorphite or gahnite), while 50% to 70% of Zn was incorporated into newly formed Zn precipitates. Contrary to the non-treated soil, the treated soil did not contain gahnite or sphalerite; it is possible that these minerals were dissolved under the higher pH conditions at the time of treatment. Desorption experiments, using a stirred flow technique with a 0.1 mol/L CaCl2 (pH 6.5) and a HNO3 (pH 4.0) solution were employed to determine the exchangeable Zn fraction and the Zn fraction which will be mobilized under more extreme weathering conditions, respectively. No significant differences were found in desorption behavior between the treated vs. non-treated soil. Bioavailability tests, using the R. metallidurans AE1433 biosensor showed that ∼8% of total Zn was bioavailable in both the treated and non-treated soils. It was concluded that the incorporation of Zn into newly formed precipitates in both the treated and non treated soils leads to a significant natural attenuation of the exchangeable/bioavailable Zn fraction at near neutral pH conditions. At lower pHs, conditions not favorable to the formation of Zn precipitates, the pool of Zn associated with the secondary Zn precipitates is potentially more bioavailable. [Copyright &y& Elsevier]

Abstract: X-Ray absorption near-edge structure (XANES) spectra at the Ti K-edge of TiO2 (rutile and anatase phases) have been analyzed. Theoretical analyses of the experimental data have been performed on the basis of both real-space full multiple scattering theory with muffin-tin approximation for potential shape and full-potential (beyond muffin-tin approximation) finite difference method. A full potential is required to satisfactorily reproduce experimental Ti K-edge XANES spectra in the TiO2. [Copyright &y& Elsevier]

X-ray emission spectra recorded in the off-resonant regime carry information on the density of unoccupied states. It is known that by employing the Kramers-Heisenberg formalism, the high energy resolution off-resonant spectroscopy (HEROS) is equivalent to the x-ray absorption spectroscopy (XAS) technique and provides the same electronic state information. Moreover, in the present Letter we demonstrate that the shape of HEROS spectra is not modified by self-absorption effects. Therefore, in contrast to the fluorescence-based XAS techniques, the recorded shape of the spectra is independent of the sample concentration or thickness. The HEROS may thus be used as an experimental technique when precise information about specific absorption features and their strengths is crucial for chemical speciation or theoretical evaluation. [ABSTRACT FROM AUTHOR]