TY - JOUR A1 - Hennig, C. A1 - Ikeda-Ohno, A. A1 - Kraus, Werner A1 - Weiss, S. A1 - Pattison, P. A1 - Emerich, H. A1 - Abdala, P. M. A1 - Scheinost, A.C. T1 - Crystal structure and solution species of Ce(III) and Ce(IV) formates: From mononuclear to hexanuclear complexes N2 - Cerium(III) and cerium(IV) both form formate complexes. However, their species in aqueous solution and the solid-state structures are surprisingly different. The species in aqueous solutions were investigated with Ce K-edge EXAFS spectroscopy. Ce(III) formate shows only mononuclear complexes, which is in agreement with the predicted mononuclear species of Ce(HCOO)2+ and Ce(HCOO)2+. In contrast, Ce(IV) formate forms in aqueous solution a stable hexanuclear complex of [Ce6(µ3-O)4(µ3-OH)4(HCOO)x(NO3)y]12–x-y. The structural differences reflect the different influence of hydrolysis, which is weak for Ce(III) and strong for Ce(IV). Hydrolysis of Ce(IV) ions causes initial polymerization while complexation through HCOO– results in 12 chelate rings stabilizing the hexanuclear Ce(IV) complex. Crystals were grown from the above-mentioned solutions. Two crystal structures of Ce(IV) formate were determined. Both form a hexanuclear complex with a [Ce6(µ3-O)4(µ3-OH)4]12+ core in aqueous HNO3/HCOOH solution. The pH titration with NaOH resulted in a structure with the composition [Ce6(µ3-O)4(µ3-OH)4(HCOO)10(NO3)2(H2O)3]·(H2O)9.5, while the pH adjustment with NH3 resulted in [Ce6(µ3-O)4(µ3-OH)4(HCOO)10(NO3)4]·(NO3)3(NH4)5(H2O)5. Furthermore, the crystal structure of Ce(III) formate, Ce(HCOO)3, was determined. The coordination polyhedron is a tricapped trigonal prism which is formed exclusively by nine HCOO– ligands. The hexanuclear Ce(IV) formate species from aqueous solution is widely preserved in the crystal structure, whereas the mononuclear solution species of Ce(III) formate undergoes a polymerization during the crystallization process. KW - Crystal structure KW - Ce complexes KW - EXAFS KW - XANES PY - 2013 DO - https://doi.org/10.1021/ic400999j SN - 0020-1669 SN - 1520-510X VL - 52 IS - 20 SP - 11734 EP - 11743 PB - American Chemical Society CY - Washington, DC AN - OPUS4-29850 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Grehn, M. A1 - Reinhardt, F. A1 - Bonse, Jörn A1 - Eberstein, M. A1 - Seuthe, T. T1 - Response to "comment on 'femtosecond laser-induced modification of potassium-magnesium silicate glasses: an analysis of structural changes by near edge x-ray absorption spectroscopy'" KW - Bond lengths KW - Glass KW - High-speed optical techniques KW - Magnesium compounds KW - Monochromators KW - Potassium compounds KW - Silicon compounds KW - XANES PY - 2013 DO - https://doi.org/10.1063/1.4804148 SN - 0003-6951 SN - 1077-3118 VL - 102 SP - 196102-1 - 196102-2 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-28520 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Darlatt, Erik A1 - Nefedov, A. A1 - Traulsen, C.H.-H. A1 - Poppenberg, J. A1 - Richter, S. A1 - Dietrich, Paul A1 - Lippitz, Andreas A1 - Illgen, René A1 - Kühn, Julius A1 - Schalley, C.A. A1 - Wöll, Ch. A1 - Unger, Wolfgang T1 - Interperetation of experimental N K NEXAFS of azide, 1,2,3-triazole and terpyridyl groups by DFT spectrum simulations N2 - Experimental N K-edge NEXAFS data of surface immobilized azide, 1,2,3-triazole and terpyridyl groups are interpreted with the help of DFT spectrum simulations. Assignments of π* resonances in experimental N K-edge NEXAFS spectra to nitrogen atoms within these functional groups have been made. The azide was immobilized on gold as the head group of a thiol SAM, 1,2,3-triazole was formed on this SAM by click reaction and terpyridyl groups were introduced as substituents of the acetylene used for the click reaction. For azide-terminated molecules, DFT spectrum simulations are found to be useful to find measurement conditions delivering experimental N K-edge NEXAFS data with negligible X-ray damage. The 1,2,3-triazole group is found to be rather stable under X-ray irradiation. KW - N K-edge NEXAFS KW - XANES KW - Surface click chemistry KW - Density functional theory KW - Azide KW - 1,2,3-Triazole PY - 2012 DO - https://doi.org/10.1016/j.elspec.2012.09.008 SN - 0368-2048 SN - 1873-2526 VL - 185 IS - 12 SP - 621 EP - 624 PB - Elsevier CY - Amsterdam AN - OPUS4-27774 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mandel, K. A1 - Szczerba, Wojciech A1 - Thünemann, Andreas A1 - Riesemeier, Heinrich A1 - Girod, Matthias A1 - Sextl, G. T1 - Nitric acid-stabilized superparamagnetic iron oxide nanoparticles studied with X-rays N2 - Agglomerated superparamagnetic iron oxide nanoparticles can easily and in large scale be precipitated from iron salt solutions. Although the process is well known, it is ambiguously either assumed that magnetite or maghemite is obtained. The first part of our study clarifies this question using X-ray absorption spectroscopy. For further processing of the nanoparticles, i.e., for giving them a surface functionality or incorporating them into composites, it is important to break the agglomerates and individualize the particles at first. This can effectively be done with nitric acid treatment. The influence of this process on the particles chemistry and structure was analyzed in great detail using X-ray diffraction, X-ray absorption, and smallangle X-ray scattering. In contrast to our expectation, no oxidation from magnetite (Fe3O4) to maghemite (γ- Fe2O3) was found; the formal valence of the particles in any case is magnetite (Fe3O4). Instead, an increase in the particles' surface disorder was discovered from X-ray absorption analyses and high-resolution transmission electron microscopy. The acid treatment roughens and distorts the surface of the nanoparticles which is connected with an increased spin disorder. KW - XANES KW - EXAFS KW - SAXS KW - Coprecipitation KW - Iron oxide spectra KW - Ferrofluid PY - 2012 DO - https://doi.org/10.1007/s11051-012-1066-3 SN - 1388-0764 SN - 1572-896X VL - 14 IS - 8 SP - 1066/1 EP - 9 PB - Kluwer CY - Dordrecht AN - OPUS4-26357 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Seuthe, T. A1 - Höfner, M. A1 - Reinhardt, F. A1 - Tsai, W.J. A1 - Bonse, Jörn A1 - Eberstein, M. A1 - Eichler, H.J. A1 - Grehn, M. T1 - Femtosecond laser-induced modification of potassium-magnesium silicate glasses: An analysis of structural changes by near edge x-ray absorption spectroscopy N2 - The effects of femtosecond laser pulse irradiation on the glass structure of alkaline silicate glasses were investigated by x-ray absorption near edge structure spectroscopy using the beamline of the Physikalisch-Technische Bundesanstalt at the electron synchrotron BESSY II in Berlin (Germany) by analyzing the magnesium Κ-edge absorption peak for different laser fluences. The application of fluences above the material modification threshold (2.1 J/cm²) leads to a characteristic shift of ~1.0 eV in the Κ-edge revealing a reduced (~3%) mean magnesium bond length to the ligated oxygen ions (Mg-O) along with a reduced average coordination number of the Mg ions. KW - Glass KW - Glass structure KW - Laser beam effects KW - Magnesium compounds KW - Potassium compounds KW - XANES PY - 2012 DO - https://doi.org/10.1063/1.4723718 SN - 0003-6951 SN - 1077-3118 VL - 100 IS - 22 SP - 224101-1 EP - 224101-3 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-25918 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Darlatt, Erik A1 - Traulsen, C.H.-H. A1 - Poppenberg, J. A1 - Richter, S. A1 - Kühn, Julius A1 - Schalley, C.A. A1 - Unger, Wolfgang T1 - Evidence of click and coordination reactions on a self-assembled monolayer by synchrotron radiation based XPS and NEXAFS N2 - An ethynylterpyridine was 'clicked' to an azide-terminated self-assembled monolayer on gold and characterized by synchrotron radiation based surface analysis as NEXAFS and XPS. The detection of azide and terpyridine signatures confirmed a partial click reaction at room temperature. The absence of the azides after reaction at 50 °C indicates an almost complete conversion. For the latter case successful Pd(II) coordination has been proven. The Au–S interface of the SAMs has been characterized by S 1s and S 2p XPS. KW - Synchrotron radiation XPS KW - NEXAFS spectroscopy KW - Surface click chemistry KW - Self-assembled monolayer KW - HAXPES KW - XANES PY - 2012 DO - https://doi.org/10.1016/j.elspec.2012.02.004 SN - 0368-2048 SN - 1873-2526 VL - 185 IS - 3-4 SP - 85 EP - 89 PB - Elsevier CY - Amsterdam AN - OPUS4-25596 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Polte, Jörg A1 - Kraehnert, R. A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Riesemeier, Heinrich A1 - Thünemann, Andreas A1 - Emmerling, Franziska T1 - New insights of the nucleation and growth process of gold nanoparticles via in situ coupling of SAXS and XANES N2 - Although metallic nanoparticles play an important role in the area of nanotechnology, a coherent mechanistic explanation for the evolution of the particles during their chemical synthesis has not yet been provided in many cases. To gain a profound understanding of the growth mechanism of colloidal nanoparticles, new approaches using Small Angle X-Ray Scattering (SAXS) combined with X-ray absorption near-edge structure (XANES) are presented. This combination allows for insights into two prominent syntheses routes of gold nanoparticles (GNP): The 'slow' reaction using sodium citrate (30-90 min) as a reducing agent and the 'fast' reaction employing NaBH4 (within few seconds). In the first case data derived with the coupled XANES and SAXS suggests a four-step particle formation mechanism. For the second system a time resolution in the order of 100-200 ms was achieved by coupling a common laboratory SAXS instrument with a microstructured mixer, which allows data acquisition in a continuous-flow mode. The results indicate a coalescence driven growth process. Based on the capabilities to deduce the size, number and polydispersity of the particles, the results of both methods enable the development of mechanistic schemes explaining the different phases of particle formation and growth, thus providing a basis for improved control over the synthesis processes. KW - SAXS KW - XANES KW - Nanoparticle formation PY - 2010 DO - https://doi.org/10.1088/1742-6596/247/1/012051 SN - 1742-6588 SN - 1742-6596 VL - 247 IS - 1 SP - 012051-1 - 012051-10 PB - IOP Publ. CY - Bristol, UK AN - OPUS4-22684 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Polte, Jörg A1 - Herder, Martin A1 - Erler, Robert A1 - Rolf, Simone A1 - Fischer, A. A1 - Würth, Christian A1 - Thünemann, Andreas A1 - Kraehnert, R. A1 - Emmerling, Franziska T1 - Mechanistic insights into seeded growth processes of gold nanoparticles N2 - A facile approach for the synthesis of monodisperse gold nanoparticles with radii in the range of 7 to 20 nm is presented. Starting from monodisperse seeds with radii of 7 nm, produced in the first step, the addition of a defined amount of additional precursor material permits distinct size regulation and the realization of predicted nanoparticle sizes. These information were derived from ex- and in situ investigations by comprehensive small angle X-ray scattering (SAXS), X-ray absorption near edge structure (XANES) and UV-Vis data to obtain information on the physicochemical mechanisms. The obtained mechanisms can be transferred to other seeded growth processes. Compared to similar approaches, the presented synthesis route circumvents the use of different reducing or stabilizing agents. The size of resulting nanoparticles can be varied over a large size range presented for the first time without a measurable change in the shape, polydispersity or surface chemistry. Thus, the resulting nanoparticles are ideal candidates for size dependence investigations. KW - Gold nanoparticles KW - SAXS KW - XANES KW - Growth mechanism PY - 2010 DO - https://doi.org/10.1039/c0nr00541j SN - 2040-3364 SN - 2040-3372 VL - 2 IS - 11 SP - 2463 EP - 2469 PB - RSC Publ. CY - Cambridge AN - OPUS4-22346 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Strub, Erik A1 - Plarre, Rüdiger A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Riesemeier, Heinrich A1 - Schoknecht, Ute A1 - Urban, Klaus A1 - Jüngel, P. T1 - Determination of Cr(VI) in wood specimen: A XANES study at the Cr K edge N2 - The content of chromium in different oxidation states in chromium-treated wood was studied with XANES (X-ray absorption near-edge structure) measurements at the Cr K absorption edge. It could be shown that wood samples treated with Cr(VI) (pine and beech) did still contain a measurable content of Cr(VI) after four weeks conditioning. If such wood samples were heat exposed for 2 h with 135 °C prior conditioning, Cr(VI) was no longer detected by XANES, indicating a complete reduction to chromium (III). KW - X-ray spectroscopy KW - XANES KW - XAS KW - XRF KW - Specifikation KW - Reduction PY - 2008 DO - https://doi.org/10.1016/j.nimb.2008.03.011 SN - 0168-583X SN - 1872-9584 VL - 266 IS - 10 SP - 2405 EP - 2407 PB - Elsevier CY - Amsterdam AN - OPUS4-17555 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Strub, Erik A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Riesemeier, Heinrich A1 - Reznikova, E. T1 - Measurements with compound refractive lenses at the "BAMline" N2 - A set of compound refractive lenses (CRLs), mounted on a silicon wafer, was obtained from the Institut für Mikrostrukturtechnik Karlsruhe. The CRLs were characterized at the BAMline at the synchrotron BESSYII in Berlin. It could be demonstrated that beam diameters below 1 µm can be obtained. The beam size accepted by the lenses is (140 × 140) µm2, thus the intensity gain in the micrometer spot, including absorption, is about 15,000. It is possible to switch between different beam energies within a few minutes. First results of scans and the application of the lenses for MicroXANES (X-ray absorption near-edge structure) measurements are presented in this paper. Also, the possibility of MicroEXAFS (extended X-ray absorption fine structure) measurements is discussed. KW - X-ray optics KW - XANES KW - EXAFS KW - XAS KW - XRF KW - Speciation PY - 2008 DO - https://doi.org/10.1016/j.nimb.2008.02.057 SN - 0168-583X SN - 1872-9584 VL - 266 IS - 10 SP - 2165 EP - 2168 PB - Elsevier CY - Amsterdam AN - OPUS4-17554 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -