@article{WilkePartzschWelteretal.2007, author = {Wilke, Max and Partzsch, G. M. and Welter, E. and Farges, Francois}, title = {Redox Reaction In Silicate Melts Monitored By Static In-Situ Fe K-edge XANES Up To 1180 C}, year = {2007}, language = {en} } @article{WilkePartzschSchmidtetal.2004, author = {Wilke, Max and Partzsch, G. M. and Schmidt, C. and Farges, Francois}, title = {In-situ study of the iron species in silicate melts}, issn = {0016-7037}, year = {2004}, language = {en} } @article{WilkePartzschFarges2004, author = {Wilke, Max and Partzsch, G. M. and Farges, Francois}, title = {XAFS of iron in silicate melt at high temperature}, issn = {0024-4937}, year = {2004}, language = {en} } @article{WilkePartzschBernhardtetal.2004, author = {Wilke, Max and Partzsch, G. M. and Bernhardt, Rita and Lattard, D.}, title = {Determination of the iron oxidation state in basaltic glasses using XANES at the K-edge}, issn = {0009-2541}, year = {2004}, abstract = {Fe K-edge X-ray absorption near edge structure (XANES) and Mossbauer spectra were collected on synthetic glasses of basaltic composition and of glasses on the sodium oxide-silica binary to establish a relation between the pre- edge of the XANES at the K-edge and the Fe oxidation state of depolymerised glasses. Charges of sample material were equilibrated at ambient pressure, superliquidus temperatures and oxygen fugacities that were varied over a range of about 15 orders of magnitude. Most experiments were carried out in gas-flow furnaces, either with pure oxygen, air, or different CO/CO2 mixtures. For the most reduced conditions, the samples charges were enclosed together with a pellet of the IQF oxygen buffer in an evacuated silica glass ampoule. Fe3+/SigmaFe x 100 of the samples determined by Mossbauer spectroscopy range between 0\% and 100\%. Position and intensity of the pre-edge centroid position vary strongly depending on the Fe oxidation state. The pre-edge centroid position and the Fe oxidation state determined by Mossbauer spectroscopy are nonlinearly related and have been fitted by a quadratic polynomial. Alternatively, the ratio of intensities measured at positions sensitive to Fe2+ and Fe3+, respectively, provides an even more sensitive method. Pre- edge intensities of the sample suite indicate average Fe co-ordination between 4 and 6 for all samples regardless of oxidation state. A potential application of the calibration given here opens the possibility of determining Fe oxidation state in glasses of similar compositions with high spatial resolution by use of a Micro-XANES setup (e.g., glass inclusions in natural minerals). (C) 2004 Elsevier B.V. All rights reserved}, language = {en} } @article{WilkePartzschBernhardtetal.2005, author = {Wilke, Max and Partzsch, G. M. and Bernhardt, Rita and Lattar, D.}, title = {Determination of the iron oxidation state in basaltic glasses using XANES at the K-edge}, issn = {0009-2541}, year = {2005}, abstract = {Fe K-edge X-ray absorption near edge structure (XANES) and Mossbauer spectra were collected on synthetic glasses of basaltic composition and of glasses on the sodium oxide-silica binary to establish a relation between the pre- edge of the XANES at the K-edge and the Fe oxidation state of depolymerised glasses. Charges of sample material were equilibrated at ambient pressure, superliquidus temperatures and oxygen fugacities that were varied over a range of about 15 orders of magnitude. Most experiments were carried out in gas-flow furnaces, either with pure oxygen, air, or different CO/CO2 mixtures. For the most reduced conditions, the samples charges were enclosed together with a pellet of the IQF oxygen buffer in an evacuated silica glass ampoule. Fe3+/Sigma Fe x 100 of the samples determined by Mossbauer spectroscopy range between 0\% and 100\%. Position and intensity of the pre-edge centroid position vary strongly depending on the Fe oxidation state. The pre-edge centroid position and the Fe oxidation state determined by Mossbauer spectroscopy are nonlinearly related and have been fitted by a quadratic polynomial. Alternatively, the ratio of intensities measured at positions sensitive to Fe2+ and Fe3+, respectively, provides an even more sensitive method. Pre- edge intensities of the sample suite indicate average Fe co-ordination between 4 and 6 for all samples regardless of oxidation state. A potential application of the calibration given here opens the possibility of determining Fe oxidation state in glasses of similar compositions with high spatial resolution by use of a Micro-XANES setup (e.g., glass inclusions in natural minerals). (c) 2004 Elsevier B.V. All rights reserved}, language = {en} } @article{WilkeFargesPartzschetal.2007, author = {Wilke, Max and Farges, Francois and Partzsch, G. M. and Schmidt, C. and Behrens, Harald}, title = {Speciation of Fe in silicate glasses and melts by in-situ XANES spectroscopy}, year = {2007}, language = {en} }