TY - JOUR A1 - Jung, S. A1 - Renz, F. A1 - Klein, M. A1 - Menzel, Michael A1 - Boca, R. A1 - Stößer, R. T1 - Molecular switching in iron complexes bridged via tincyanides observed by Mössbauer and ESR spectroscopy N2 - The precursor [FeIII(L)Cl] (LH2 = N,N'-bis(2'-hydroxy-3'-X-benzyliden)-1,6-diamino-3-N-hexane) is a high-spin (S = 5/2) complex (with X = -CH3, -O-CH3). This precursor is combined with the bridging unit [SnIV(CN)4] to yield star-shaped pentanuclear clusters, [(L-X-FeIII)4Sn(CN)4]Cl4 57Fe-Mössbauer, 119mSn-Mössbauer, and ESR spectroscopy are used to study our samples. For X = -CH3 the 57Fe-Mössbauer data show a multiple spin transition between iron(III) in the high-spin and low-spin state. Changing the functional group from X = -CH3 to X = -O-CH3 turns the switchability off. KW - Switching iron complexes KW - Spin-transition KW - Mössbauer spectroscopy KW - ESR-spectroscopy PY - 2010 DO - https://doi.org/10.1088/1742-6596/217/1/012027 SN - 1742-6588 SN - 1742-6596 VL - 217 IS - 1 / 012027 SP - 1 EP - 6 PB - IOP Publ. CY - Bristol, UK AN - OPUS4-22561 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mehner, Hartmut A1 - Menzel, Michael A1 - Nofz, Marianne T1 - Laboratory Intercomparison on the Determination of the Fe(II)/Fe(III) Ratio in Glass Using Mössbauer Spectroscopy N2 - The Mössbauer community all over the world was given the opportunity to determine the Fe(II)/Fe(III) ratio in 4 glass samples of different total iron content, to classify themselves with respect to their measurement technique and especially to their kind of evaluation. KW - Mössbauer spectroscopy KW - Iron KW - Glass KW - Intercomparison KW - Fe(II)/Fe(III) ratio PY - 2004 DO - https://doi.org/10.1023/B:HYPE.0000043252.55048.63 SN - 0304-3843 SN - 1572-9540 VL - 156-157 SP - 347 EP - 352 PB - Kluwer CY - Dordrecht AN - OPUS4-4579 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Maltsev, Yuri A1 - Mehner, Hartmut A1 - Menzel, Michael A1 - Maslova, Natalija A1 - Rogozev, B. A1 - Kruglov, E. ED - Thomas, M. ED - Williams, J. ED - Gibb, T. T1 - Baseline investigation in transmission Mössbauer spectroscopy using resonance detectors T2 - 26th International Conference on the Applications of the Mössbauer Effect (ICAME 2001) CY - Oxford, England, UK DA - 2001-09-02 KW - Mössbauer spectroscopy KW - Resonance detector KW - Rayleigh scattering of Mössbauer radiation PY - 2003 SN - 1-402-01087-7 SN - 0304-3843 VL - 5 SP - 9 EP - 12 PB - Kluwer Acad. Publ. CY - Dordrecht AN - OPUS4-6930 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heinrich, F. A1 - Schmidt, C. A1 - Löffler, E. A1 - Menzel, Michael A1 - Grünert, W. T1 - Fe-ZSM-5 Catalysts for the Selective Reduction of NO by Isobutane - The Problem of the Active Sites N2 - Relations between the structure of Fe–ZSM-5 catalysts prepared by interaction of FeCl3 with H–ZSM-5 and their catalytic behavior in the SCR of NO by isobutane were investigated by combining results of catalytic studies (1000 ppm NO, 1000 ppm isobutane, and 2% O2 in He, 30,000 h-1) and of physicochemical characterization (XRD, EXAFS, Mössbauer spectroscopy, TPR, IR, XPS). By variation of the preparation conditions (method of FeCl3 introduction—chemical vapor deposition or solid-state ion exchange, washing intensity, calcination regime) and of the matrix (H–ZSM-5 with normal and high defect density), Fe–ZSM-5 materials with strongly varying properties (aggregation degree of the Fe phase, acidity) were obtained. Significant discrepancies between conclusions derived from EXAFS, TPR, and Mössbauer spectroscopy were ascribed to a preference of Mössbauer spectroscopy for the detection of aggregated phases and a high defectivity of Fe oxide clusters formed upon calcination. The critical step for the preparation of a highly disperse Fe phase is extensive washing after Fe introduction. The catalytic behavior of overexchanged Fe–ZSM-5 materials prepared by interaction of FeCl3 with H–ZSM-5 of normal defect density was not influenced by aggregation of a significant part of the Fe phase. The comparison of their catalytic properties with those of a Fe2O3/H–ZSM-5 mechanical mixture and of catalysts prepared by aqueous ion exchange or by CVD of FeCl3 into H–ZSM-5 of high defect density implies that the particular activity of overexchanged Fe–ZSM-5 arises from minority sites. In these, the Fe ions are probably isolated. Other Fe sites of low nuclearity appear to add to the activity. The poor SCR performance (at a given ability for isobutane activation) of Fe–ZSM-5 prepared with a defective ZSM-5 matrix may indicate that the Fe sites which provi de the particular activity of overexchanged Fe–ZSM-5 require the cooperation of acidic sites. KW - deNOx KW - Hydrocarbons KW - Isobutane KW - Fe-ZSM-5 KW - EXAFS KW - Mössbauer spectroscopy KW - Temperature-programmed reduction PY - 2002 DO - https://doi.org/10.1006/jcat.2002.3775 SN - 0021-9517 SN - 1090-2694 VL - 212 SP - 157 EP - 172 PB - Acad. Press CY - San Diego, Calif. AN - OPUS4-2258 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmauke, T. A1 - Menzel, Michael A1 - Roduner, E. T1 - Magnetic properties and oxidation state of iron in bimetallic Pt-Fe/KL zeolite catalysts N2 - In view of an understanding of catalytic efficiency the electronic and magnetic state of iron in Fe/KL and the influence of Pt on these properties in Pt-Fe/KL were investigated by superconducting quantum interference device (SQUID) magnetization measurements and Mössbauer spectroscopy. After calcination in air, iron is present only as Fe3+ ions in both samples, mainly in a paramagnetic state. There is also a small antiferromagnetic contribution, probably due to iron oxide and hydroxide particles which precipitate on the outer surface of the zeolite crystallites during preparation. After reduction in H2, the behavior of both samples is predominantly superparamagnetic, but the presence of Pt increases both the saturation magnetization and the size of the residual hysteresis loop. At the same there remains a pronounced paramagnetic contribution which appears to be even slightly higher than before reduction. The interpretation is that alloy particles of metallic Pt–Fe are formed on the outer surface. Since small clusters inside the zeolite crystallites are most active for catalysis the alloy formation seems to be not of relevance for an enhancement of sulfur resistance. It was also shown that during reduction a fraction of Fe2+ is formed. The coordination of the Fe2+ ions is clearly influenced by Pt and it seems very likely that Fe2+ ions are in close contact with Pt clusters. This interaction is probably the origin of the enhanced sulfur resistance and catalytic activity in the reforming reactions. KW - Pt-Fe/KL zeolite KW - SQUID magnetization measurements KW - Mössbauer spectroscopy KW - Oxidation state of iron KW - Pt-Fe alloy PY - 2003 DO - https://doi.org/10.1016/S1381-1169(02)00522-8 SN - 1381-1169 SN - 1873-314X VL - 194 SP - 211 EP - 225 PB - Elsevier CY - Amsterdam AN - OPUS4-2296 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cieslak, J. A1 - Dubiel, S.M. A1 - Eichhorn, F. A1 - Menzel, Michael A1 - Reuther, H. T1 - Investigation of single-crystals of chromium implanted with 119Sn-ions of various energies N2 - Single-crystals of chromium doped with 10 16 119Sn ions per cm2 and energies ranging between 45 and 190 keV were investigated with conversion electron Mössbauer spectroscopy (CEMS), Auger electron spectroscopy (AES), grazing angle X-ray diffraction (GAXRD), and scanning electron microscopy (SEM). The Mössbauer spectra were found to be significantly different than those of the bulk. Both the maximum and the average hf. field values were higher by a factor of ˜3 than the corresponding quantities for the bulk. The overall shape of the spectra is also different. GAXRD study has revealed that the near-surface zone of the investigated samples has a nanocrystalline structure with the average size of grains ranging between ˜20 and ˜40 nm. The latter seems to be the main reason for the observed enhancement of the spin-density and its distortion. KW - Magnetically ordered materials KW - Crystal growth KW - Hyperfine interactions KW - Mössbauer spectroscopy PY - 2007 DO - https://doi.org/10.1016/j.jallcom.2006.07.143 SN - 0925-8388 SN - 1873-4669 VL - 442 IS - 1-2 SP - 235 EP - 238 PB - Elsevier Sequoia CY - Lausanne AN - OPUS4-15730 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mehner, Hartmut A1 - Menzel, Michael A1 - Müller, J.-P. A1 - Gähde, J. A1 - Güttler, B. T1 - Plasma-assisted transformation of iron surfaces into magnetite KW - Iron KW - Magnetite KW - Mössbauer spectroscopy KW - Plasma oxidation PY - 1999 SN - 0257-8972 VL - 116-119 SP - 367 EP - 369 PB - Elsevier Science CY - Lausanne AN - OPUS4-773 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lucka, R. A1 - Elshani, B. A1 - Kilic, M. S. A1 - Klimke, S. A1 - Krüger, C. A1 - Menzel, Michael A1 - Stößer, R. A1 - Titiš, J. A1 - Boča, R. A1 - Renz, F. T1 - ESR and Mössbauer spectroscopy of iron(III) spin crossover complexes based on pentadentate Schiff base ligands with pseudohalide coligands N2 - Two iron(III) spin crossover complexes [Fe(5Cl-L)(NCS)] (1) and [Fe(5Cl-L)(NCSe)] (2) were synthesized with the pentadentate Schiff base ligand 5Cl-L and thiocyanato and selenocyanato as coligands. 5Cl-L, as an asymmetric {N3O2} donor Schiff base, was synthesized by a condensation reaction of 5-chlorosalicyladehyde using the asymmetric N-(2-aminoethyl)-1,3-propanediamine. The complexes exhibited a spin crossover at 280 (1) and 293 K (2), respectively, and were subjected to electron spin resonance (ESR) and Mössbauer spectroscopy at 77, 295 and 325 K. Ab initio CASSCF calculations followed by the NEVPT2 method were applied for predicting the g-tensor components as well as Mössbauer parameters. KW - Spin crossover KW - Iron(III) complexes KW - Mössbauer spectroscopy KW - ESR spectroscopy KW - Ab initio calculations PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-634061 DO - https://doi.org/10.3390/magnetochemistry11050043 SN - 2312-7481 VL - 11 IS - 5 SP - 1 EP - 9 PB - MDPI CY - Basel AN - OPUS4-63406 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lindner, A. A1 - Menzel, Michael A1 - Renz, F. A1 - Kurth, D.G. A1 - Thünemann, Andreas T1 - Metallosupramolecular coordination polyelectrolytes investigated by Mössbauer spectroscopy N2 - Metallosupramolecular coordination polyelectrolytes (MEPEs) based on rigid and flexible ditopic bis-terpyridine ligands and Fe(II) ions are investigated by Mössbauer spectroscopy. We demonstrate the influence of mechanical stress induced by grinding on the structure of MEPE as well as the ability of MEPE to self-repair through recrystallisation. KW - Metallosupramolecular coordination polyelectrolyte KW - Bis-terpyridine KW - Mössbauer spectroscopy KW - Supramolecular chemistry PY - 2005 UR - http://www.edoc.mpg.de/298371 SN - 0304-3843 SN - 1572-9540 VL - 166 IS - 1-4 SP - 465 EP - 468 PB - Kluwer CY - Dordrecht AN - OPUS4-15729 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kolb, U. A1 - Büscher, K. A1 - Helm, C.A. A1 - Lindner, A. A1 - Thünemann, Andreas A1 - Menzel, Michael A1 - Higuchi, M. A1 - Kurth, D.G. T1 - The solid-state architecture of a metallosupramolecular polyelectrolyte N2 - Self-assembly of Fe(II) and the ditopic ligand 1,4-bis(2,2':6',2"-terpyridine-4'-yl)benzene results in equilibrium structures in solutions, so-called metallosupramolecular coordination polyelectrolytes (MEPEs). It is exceedingly difficult to characterize such macromolecular assemblies, because of the dynamic nature. Therefore, hardly any structural information is available for this type of material. Here, we show that from dilute solutions, where small aggregates predominate, it is possible to grow nanoscopic crystals at an interface. A near atomic resolution structure of MEPE is obtained by investigating the nanoscopic crystals with electron diffraction in combination with molecular modeling. The analysis reveals a primitive monoclinic unit cell (P21/c space group, a = 10.4 Å, b = 10.7 Å, c = 34.0 Å, α = γ = 90°, β = 95°, ρ = 1.26 g/cm³, and Z = 4). The MEPE forms linear rods, which are organized into sheets. Four sheets intersect the unit cell, while adjacent sheets are rotated by 90° with respect to each other. The pseudooctahedral coordination geometry of the Fe(II) centers is confirmed by Mössbauer spectroscopy. The combination of diffraction and molecular modeling presented here may be of general utility to address problems in structural materials science. KW - Polymer KW - Polyelectrolyte KW - Electron diffraction KW - Mössbauer spectroscopy KW - Molecular modeling KW - Supramolecular chemistry PY - 2006 SN - 0027-8424 SN - 1091-6490 VL - 103 IS - 27 SP - 10202 EP - 10206 PB - National Academy of Sciences CY - Washington, DC AN - OPUS4-12495 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -