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21	Hydrogen electrochemistry in room temperature ionic liquids Meng, Yao January 2012 (has links) This thesis primarily focuses on the electrochemical properties of the H<sub>2</sub>/H<sup>+</sup> redox couple, at various metallic electrodes in room temperature ionic liquids. Initially, a comprehensive overview of room temperature ionic liquids, RTILs, compared to conventional organic solvents is presented which identifies their favourable properties and applications, followed by a second chapter describing the basic theory of electrochemistry. A third chapter presents the general experimental reagents, instruments and measurements used in this thesis. The results presented in this thesis are summarized in six further chapters and shown as follows. (1) Hydrogenolysis, hydrogen loaded palladium electrodes by electrolysis of H[NTf<sub>2</sub>] in a RTIL [C<sub>2</sub>mim][NTf<sub>2</sub>]. (2) Palladium nanoparticle-modified carbon nanotubes for electrochemical hydrogenolysis in RTILs. (3) Electrochemistry of hydrogen in the RTIL [C<sub>2</sub>mim][NTf<sub>2</sub>]: dissolved hydrogen lubricates diffusional transport. (4) The hydrogen evolution reaction in a room temperature ionic liquid: mechanism and electrocatalyst trends. (5) The formal potentials and electrode kinetics of the proton_hydrogen couple in various room temperature ionic liquids. (6) The electroreduction of benzoic acid: voltammetric observation of adsorbed hydrogen at a Platinum microelectrode in room temperature ionic liquids. The first two studies show electrochemically formed adsorbed H atoms at a metallic Pt or Pd surface can be used for clean, efficient, safe electrochemical hydrogenolysis of organic compounds in RTIL media. The next study shows the physicochemical changes of RTIL properties, arising from dissolved hydrogen gas. The last three studies looked at the electrochemical properties of H<sub>2</sub>/H<sup>+</sup> redox couple at various metallic electrodes over a range of RTILs vs a stable Ag/Ag<sup>+</sup> reference couple, using H[NTf<sub>2</sub>] and benzoic acid as proton sources. The kinetic and thermodynamic mechanisms of some reactions or processes are the same in RTILs as in conventional organic or aqueous solvents, but other remarkably different behaviours are presented. Most importantly significant constants are seen for platinum, gold and molybdenum electrodes in term of the mechanism of proton reduction to form hydrogen. 541
22	Investigation of the growth process of thin iron oxide films: Analysis of X-ray Photoemission Spectra by Charge Transfer Multiplet calculations Suendorf, Martin 19 December 2012 (has links) Thin metallic films with magnetic properties like magnetite are an interesting material in current technological applications. In the presented work the iron oxide films are grown by molecular beam epitaxy on MgO(001) substrates at temperatures between room temperature and 600K. The film and surface structure are investigated by x-ray reflectometry (XRR), x-ray diffraction (XRD) and low energy electron diffraction (LEED). The chemical properties are investigated by x-ray photoelectron spectroscopy (XPS). Furthermore, charge transfer multiplet (CTM) calculations are performed as a means to gain additional information from photoemission spectra. It is shown that only for temperatures higher than 500K the oxide film forms a spinel structure. A previously unobserved (2x1) surface reconstruction in two orthogonal domains is found for various preparation conditions. The application of CTMs results in good quantitative and qualitative agreement to other methods for the determination of the film stoichiometry. In addition CTMs can well describe the segregation of Mg atoms into the oxide film either during film growth or during film annealing. It is found that initially Mg substitutes Fe on all possible lattice sites, only for prolonged treatment at high temperature do Mg atoms favour the octahedral lattice sites of divalent Fe. thin films molecular beam epitaxy x-ray reflectometry x-ray diffraction low energy electron diffraction x-ray photoemission spectroscopy charge transfer multiplet 33.05 - Experimentalphysik 33.07 - Spektroskopie 61.10.Kw - X-ray reflectometry 61.10.Nz - X-ray diffraction ddc:530
23	Photodissoziation von Halogenwasserstoff- und orientierten Wasserstoff-Edelgas-Halogen-Molekülen in Clusterumgebungen / Photodissociation of hydrogen halide and oriented hydrogen-rare gas-halogen molecules in cluster environments Nahler, Nils Hendrik 28 October 2002 (has links) No description available. 530 Physik Mathematics and Computer Science Photodissoziation Cluster Halogenwasserstoff Edelgas UV Photodissoziation HBr HI HCl große Ar/sub n/ Cluster adsorbiertes Molekül eingebettes Molekül mittlere Größe Größenverteilung Energieverteilung Käfigeffekt Adsorptionsort orientierte Moleküle Gasphase Xe/sub n/ asymmetrische Verteilung gepulste Laserstrahlung elektrostatisches Feld Ausrichtung Orientierung Polarisierbarkeit Dipolmoment HXeI HXeCl Anisotropieparameter Verzweigungsverhältnis polarisierte Laserstrahlung Flugzeitmassenspektrometer Spin-Bahn Aufspaltung 243 nm 193 nm photodissociation cluster hydrogen halide rare gas UV photodissociation HBr HI HCl large Ar/sub n/ clusters adsorbed molecule embedded molecule mean size size distribution kinetic energy distribution cage effect adsorption sites oriented molecules gas phase Xe/sub n/ asymmetric distribution pulsed laser electrostatic field alignment orientation polarizability dipole moment HXeI HXeCl anisotropy parameter branching ratio polarized laser light time-of-flight mass spectrometer spin-orbit state 243 nm 193 nm 33.30 SD

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