@article{41260, author = {{Bauer, Matthias and Stalinski, Tom and Aziz, Emad F.}}, issn = {{1439-4235}}, journal = {{ChemPhysChem}}, keywords = {{Physical and Theoretical Chemistry, Atomic and Molecular Physics, and Optics}}, number = {{11}}, pages = {{2088--2091}}, publisher = {{Wiley}}, title = {{{Insights into the Induced Ultrafast Electron Delocalization in Fe(CO)5 Using Dark Channel Fluorescence Yield X-Ray Absorption}}}, doi = {{10.1002/cphc.201100243}}, volume = {{12}}, year = {{2011}}, } @article{41259, author = {{Clemens, Oliver and Bauer, Matthias and Haberkorn, Robert and Beck, Horst Philipp}}, issn = {{0044-2313}}, journal = {{Zeitschrift für anorganische und allgemeine Chemie}}, keywords = {{Inorganic Chemistry}}, number = {{7-8}}, pages = {{1036--1044}}, publisher = {{Wiley}}, title = {{{On the Existence of LiFeVO4 - Tales and Imagination}}}, doi = {{10.1002/zaac.201100037}}, volume = {{637}}, year = {{2011}}, } @article{41258, author = {{Butsch, Katharina and Klein, Axel and Bauer, Matthias}}, issn = {{0020-1693}}, journal = {{Inorganica Chimica Acta}}, keywords = {{Materials Chemistry, Inorganic Chemistry, Physical and Theoretical Chemistry}}, number = {{1}}, pages = {{350--358}}, publisher = {{Elsevier BV}}, title = {{{Highly flexible O,O′,N ligands and their Fe, Ni, Cu and Zn complexes}}}, doi = {{10.1016/j.ica.2011.02.072}}, volume = {{374}}, year = {{2011}}, } @article{25965, abstract = {{Nanoporous ZnO powders with high surface-to-mass ratios (SMR) between 15 and 70 m2 g−1 are synthesized, structurally characterized, and studied by time-resolved photoluminescence (PL). A strong dependence of the recombination dynamics and spectral width on SMR is observed at T = 10 K, and pronounced disorder-induced effects are found in the temperature dependence. Both the thermally induced shift of the PL maximum and the spectrally integrated PL intensity are interpreted by appropriate theoretical models. This consistent quantitative analysis of the experimental data yields a characteristic energy of 15 meV for the disorder scale in the nanoporous ZnO sample with an intermediate SMR.}}, author = {{Chernikov, Alexej and Horst, Swantje and Waitz, Thomas and Tiemann, Michael and Chatterjee, Sangam}}, issn = {{1932-7447}}, journal = {{The Journal of Physical Chemistry C}}, pages = {{1375--1379}}, title = {{{Photoluminescence Properties of Ordered Mesoporous ZnO}}}, doi = {{10.1021/jp104293e}}, year = {{2011}}, } @article{25962, abstract = {{We report the correlation of the aging of Pd-doped SnO2 methane sensors with the change of the oxidation state of Pd. Mesoporous SnO2 doped with palladium species was prepared and exposed to different gas mixtures at high temperature (600 °C) to simulate long term usage. After each exposure step a fraction of the sample was cooled down to “freeze” the current oxidation state of Pd which was then analyzed by X-ray Absorption Near-Edge Spectroscopy (XANES) using the 'white line' (i.e. the absorption peak corresponding to the transition from the 2p3/2 core level to unoccupied 4 d states) intensity of the L(III) edge as a probe for the oxidation state. The Pd oxidation state correlates with the response of the resistive SnO2 sensor to methane gas, as determined by measuring the gas response to different concentrations of methane. Samples treated with 5000 ppm methane in air show a significant reduction of Pd(II) to Pd(0), depending clearly on the carrier gas (synthetic air, pure nitrogen) and on the temperature (600 °C vs. 300 °C).}}, author = {{Wagner, T. and Bauer, M. and Sauerwald, T. and Kohl, C.-D. and Tiemann, Michael}}, issn = {{0040-6090}}, journal = {{Thin Solid Films}}, pages = {{909--912}}, title = {{{X-ray absorption near-edge spectroscopy investigation of the oxidation state of Pd species in nanoporous SnO2 gas sensors for methane detection}}}, doi = {{10.1016/j.tsf.2011.04.187}}, year = {{2011}}, } @article{25964, abstract = {{Capacitive sensors are the most commonly used devices for the detection of humidity because they are inexpensive and the detection mechanism is very specific for humidity. However, especially for industrial processes, there is a lack of dielectrics that are stable at high temperature (>200 °C) and under harsh conditions. We present a capacitive sensor based on mesoporous silica as the dielectric in a simple sensor design based on pressed silica pellets. Investigation of the structural stability of the porous silica under simulated operating conditions as well as the influence of the pellet production will be shown. Impedance measurements demonstrate the utility of the sensor at both low (90 °C) and high (up to 210 °C) operating temperatures.}}, author = {{Wagner, Thorsten and Krotzky, Sören and Weiß, Alexander and Sauerwald, Tilman and Kohl, Claus-Dieter and Roggenbuck, Jan and Tiemann, Michael}}, issn = {{1424-8220}}, journal = {{Sensors}}, pages = {{3135--3144}}, title = {{{A High Temperature Capacitive Humidity Sensor Based on Mesoporous Silica}}}, doi = {{10.3390/s110303135}}, year = {{2011}}, } @article{25963, abstract = {{We report the synthesis of mesoporous tin dioxide (SnO2) materials with well-defined particle morphology. The products consist of uniform spheres with a diameter of 5 μm. The spheres are hierarchically porous with two distinct pore modes of 5.0 nm and 52 nm, respectively. This special porosity is the result of a synthesis procedure which involves a ‘hard templating’ (nanocasting) process. The product forms an approximately homogeneous monolayer of spheres on a sensor substrate and shows promising response to methane gas with low cross-sensitivity to water. The structural properties and gas-sensing performance are compared with a mesoporous SnO2 material without defined morphology, prepared by a ‘soft templating’ procedure.}}, author = {{Smått, J.-H. and Lindén, M. and Wagner, T. and Kohl, C.-D. and Tiemann, Michael}}, issn = {{0925-4005}}, journal = {{Sensors and Actuators B: Chemical}}, pages = {{483--488}}, title = {{{Micrometer-sized nanoporous tin dioxide spheres for gas sensing}}}, doi = {{10.1016/j.snb.2010.12.051}}, year = {{2011}}, } @article{25961, abstract = {{Mesoporous In2O3, synthesized by a nanocasting procedure, is used as a resistive gas sensor for ozone in very low concentrations (from 20 ppb to 2.4 ppm) at room temperature. Its sensing performance is substantially increased by illumination with blue light (460 nm, 2.7 eV). For low ozone concentrations the sensor response increases with increasing humidity. However, higher humidity also results in the occurrence of a saturation of the response at lower ozone concentrations; this is rationalized by assuming a poisoning of surface active sites by hydroxyl groups.}}, author = {{Wagner, T. and Hennemann, J. and Kohl, C.-D. and Tiemann, Michael}}, issn = {{0040-6090}}, journal = {{Thin Solid Films}}, pages = {{918--921}}, title = {{{Photocatalytic ozone sensor based on mesoporous indium oxide: Influence of the relative humidity on the sensing performance}}}, doi = {{10.1016/j.tsf.2011.04.181}}, year = {{2011}}, } @article{41263, author = {{Maratini, Federica and Pandolfo, Luciano and Bendova, Maria and Schubert, Ulrich and Bauer, Matthias and Rocchia, Massimiliano and Venzo, Alfonso and Tondello, Eugenio and Gross, Silvia}}, issn = {{0020-1669}}, journal = {{Inorganic Chemistry}}, keywords = {{Inorganic Chemistry, Physical and Theoretical Chemistry}}, number = {{2}}, pages = {{489--502}}, publisher = {{American Chemical Society (ACS)}}, title = {{{From Thioxo Cluster to Dithio Cluster: Exploring the Chemistry of Polynuclear Zirconium Complexes with S,O and S,S Ligands}}}, doi = {{10.1021/ic1013768}}, volume = {{50}}, year = {{2010}}, } @article{41262, author = {{Bauer, Matthias}}, issn = {{1089-5639}}, journal = {{The Journal of Physical Chemistry A}}, keywords = {{Physical and Theoretical Chemistry}}, number = {{49}}, pages = {{12870--12874}}, publisher = {{American Chemical Society (ACS)}}, title = {{{The Chemical Information Contained in the EXAFS Debye−Waller Factor: Covalency in Iron(III) Bis-diketonato Complexes}}}, doi = {{10.1021/jp1079718}}, volume = {{114}}, year = {{2010}}, } @article{41268, author = {{Bauer, Matthias and Heusel, Gerhard and Mangold, Stefan and Bertagnolli, Helmut}}, issn = {{0909-0495}}, journal = {{Journal of Synchrotron Radiation}}, keywords = {{Instrumentation, Nuclear and High Energy Physics, Radiation}}, number = {{2}}, pages = {{273--279}}, publisher = {{International Union of Crystallography (IUCr)}}, title = {{{Spectroscopic set-up for simultaneous UV-Vis/(Q)EXAFSin situandin operandostudies of homogeneous reactions under laboratory conditions}}}, doi = {{10.1107/s0909049509054910}}, volume = {{17}}, year = {{2010}}, } @article{41266, author = {{Bauer, Matthias and Gastl, Christoph}}, issn = {{1463-9076}}, journal = {{Physical Chemistry Chemical Physics}}, keywords = {{Physical and Theoretical Chemistry, General Physics and Astronomy}}, number = {{21}}, publisher = {{Royal Society of Chemistry (RSC)}}, title = {{{X-Ray absorption in homogeneous catalysis research: the iron-catalyzed Michael addition reaction by XAS, RIXS and multi-dimensional spectroscopy}}}, doi = {{10.1039/b926385c}}, volume = {{12}}, year = {{2010}}, } @article{41264, author = {{Ene, Augusta Bianca and Bauer, Matthias and Archipov, Tanja and Roduner, Emil}}, issn = {{1463-9076}}, journal = {{Physical Chemistry Chemical Physics}}, keywords = {{Physical and Theoretical Chemistry, General Physics and Astronomy}}, number = {{24}}, publisher = {{Royal Society of Chemistry (RSC)}}, title = {{{Adsorption of oxygen on copper in Cu/HZSM5 zeolites}}}, doi = {{10.1039/c000750a}}, volume = {{12}}, year = {{2010}}, } @article{41265, author = {{Gross, Silvia and Bauer, Matthias}}, issn = {{1616-301X}}, journal = {{Advanced Functional Materials}}, keywords = {{Electrochemistry, Condensed Matter Physics, Biomaterials, Electronic, Optical and Magnetic Materials}}, number = {{23}}, pages = {{4026--4047}}, publisher = {{Wiley}}, title = {{{EXAFS as Powerful Analytical Tool for the Investigation of Organic-Inorganic Hybrid Materials}}}, doi = {{10.1002/adfm.201000095}}, volume = {{20}}, year = {{2010}}, } @article{25971, abstract = {{Precipitation of zinc sulfide particles is a very rapid process, and monitoring of the particle growth is experimentally very demanding. Applying a liquid jet flow cell, we were able to follow zinc sulfide particle formation on time scales down to 10−5 s. The flow cell was designed in such a way that data acquisition on the microsecond time scale was possible under steady-state conditions along a liquid jet (tubular reactor concept), allowing SAXS data accumulation over a time scale of minutes. We were able to monitor the growth of zinc sulfide particles and found experimental evidence for very rapid particle aggregation processes within the liquid jet. Under the experimental conditions the particle growth is controlled by mass transfer: i.e., the diffusion of the hydrogen sulfide into the liquid jet.}}, author = {{Schmidt, Wolfgang and Bussian, Patrick and Lindén, Mika and Amenitsch, Heinz and Agren, Patrik and Tiemann, Michael and Schüth, Ferdi}}, issn = {{0002-7863}}, journal = {{Journal of the American Chemical Society}}, pages = {{6822--6826}}, title = {{{Accessing Ultrashort Reaction Times in Particle Formation with SAXS Experiments: ZnS Precipitation on the Microsecond Time Scale}}}, doi = {{10.1021/ja101519z}}, year = {{2010}}, } @article{25967, abstract = {{We report the structural characterization and gas sensing properties of mesoporous SnO2 synthesized by structure replication (nanocasting) from ordered mesoporous KIT-6 silica. The products show a high thermal stability with no structural loss up to 600 °C and only minor decrease in specific surface area by 18% at 800 °C, as proven by powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), and nitrogen physisorption. In particular, the samples turn out to be much more stable than porous SnO2 materials prepared by sol–gel-based synthesis procedures for comparison. The thermal stability facilitates the utilization of the materials as sensors for combustible gases which react at high temperatures; test measurements reveal promising responses to methane (CH4) as an example.}}, author = {{Waitz, T. and Becker, B. and Wagner, T. and Sauerwald, T. and Kohl, C.-D. and Tiemann, Michael}}, issn = {{0925-4005}}, journal = {{Sensors and Actuators B: Chemical}}, pages = {{788--793}}, title = {{{Ordered nanoporous SnO2 gas sensors with high thermal stability}}}, doi = {{10.1016/j.snb.2010.08.001}}, year = {{2010}}, } @article{25972, abstract = {{In2O3 with ordered, uniform mesoporosity is prepared by nanocasting, using various porous silica phases (KIT-6, SBA-15) as structure matrices. The In2O3 particles exhibit well-defined morphologies (spherical or ellipsoidal, depending on the choice of silica matrix) and quite uniform sizes in the range of a few hundred nanometers. The regular morphology of the In2O3 particles is not associated with the morphological properties of the silica matrices. Instead, it is the result of the growth mechanism of In2O3 inside the silica pores; this mechanism is investigated in some detail. Hence, the nanocasting method offers a versatile and simple way of creating mesoporous In2O3 with regular morphology; this will be beneficial for many applications that require well-defined morphological properties, such as gas sensing or catalysis.}}, author = {{Haffer, Stefanie and Waitz, Thomas and Tiemann, Michael}}, issn = {{1932-7447}}, journal = {{The Journal of Physical Chemistry C}}, pages = {{2075--2081}}, title = {{{Mesoporous In2O3 with Regular Morphology by Nanocasting: A Simple Relation between Defined Particle Shape and Growth Mechanism}}}, doi = {{10.1021/jp910336f}}, year = {{2010}}, } @article{25968, abstract = {{We report the synthesis of monodisperse, spherical periodic mesoporous organosilica (PMO) materials. The particles have diameters between about 350 and 550 nm. They exhibit a regular core-shell structure with a solid, non-porous silica core and a mesoporous PMO shell with a thickness of approximately 75 nm and uniform pores of about 1.7 nm. The synthesis of the core and the shell is carried out in a one-pot, two-stage synthesis and can be accomplished at temperatures between 25 and 100 °C. Higher synthesis temperatures lead to substantial shrinking of the solid core, generating an empty void between core and shell. This leads to interesting cavitation phenomena in the nitrogen physisorption analysis at 77.4 K.}}, author = {{Haffer, Stefanie and Tiemann, Michael and Fröba, Michael}}, issn = {{0947-6539}}, journal = {{Chemistry - A European Journal}}, pages = {{10447--10452}}, title = {{{Periodic Mesoporous Organosilica (PMO) Materials with Uniform Spherical Core-Shell Structure}}}, doi = {{10.1002/chem.201000643}}, year = {{2010}}, } @inbook{25973, abstract = {{Chemical sensors are integral to the automation of myriad industrial processes, as well as everyday monitoring of such activities as public safety, engine performance, medical therapeutics, and many more...}}, author = {{Tiemann, Michael}}, booktitle = {{Nanostructured Materials}}, editor = {{Korotcenkov, Ghenadii}}, pages = {{291 -- 310}}, publisher = {{Momentum Press}}, title = {{{Ordered Mesoporous Films and Membranes: Synthesis, Properties and Applications in Gas Sensors}}}, volume = {{2}}, year = {{2010}}, } @article{41274, abstract = {{Abstract Yttrium methoxyethoxide Y(OEtOMe)3 is an important precursor for the sol-gel preparation of Y2O3-containing materials. Its aggregation degree and the clusters, formed in solution of 2-methoxyethanol and modified by the ligands Hacac, i PrOH and THF are studied by means of EXAFS spectroscopy. The cluster geometries of the formed complexes deviate from the well-known cyclic decameric structure of the crystalline solid Y(OEtOMe)3. A pentanuclear square-pyramidal framework, which was found for Y(OEtOMe)3, dissolved in 2-methoxyethanol in a previous study, is confirmed by a detailed discussion of the structural EXAFS parameters. While the addition of the Lewis bases i PrOH and THF does not change the aggregation degree and short range order of Y(OEtOMe)3 in solution, chelating Hacac causes a stepwise degradation of the original pentameric metal framework. Details of the degradation pathway as deduced from the EXAFS results are given, which could not be achieved by any other spectroscopic method so far. The yttrium coordination number and third cumulants, which are necessary to account for asymmetry in the individual shells, are used in order to identify structural changes of the samples in comparison with the initially formed Y5-complex.}}, author = {{Bauer, Matthias and Bertagnolli, Helmut}}, issn = {{2196-7156}}, journal = {{Zeitschrift für Physikalische Chemie}}, keywords = {{Physical and Theoretical Chemistry}}, number = {{8}}, pages = {{877--893}}, publisher = {{Walter de Gruyter GmbH}}, title = {{{Alkoxide Clusters in Solution: An EXAFS Study of the Example Y(OEtOMe)3 and the Degradation Induced by Structural Modifiers}}}, doi = {{10.1524/zpch.2009.5474}}, volume = {{223}}, year = {{2009}}, }