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51	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
52	Ultrafast Photon Management: The Power of Harmonic Nanocrystals in Nonlinear Spectroscopy and Beyond Kijatkin, Christian 01 April 2019 (has links) The present work broaches the physics of light-matter interaction, chiefly using nonlinear optical spectroscopy in a newly developed framework termed as Photon Management Concept. This way, existing fragments dealing with specific properties of harmonic and upconversion nanoparticles (HNPs/UCNPs) are consolidated into a full and coherent picture with the primary goal of understanding the underlying physical processes and their impact on the application side, especially in terms of imaging techniques, via suitable experimental and numerical studies. Contemporary optical setups involving contrast-enhancing agents are frequently limited in their excitation and detection configurations owing to a specialization to a select number of markers. As a result, the bandwidth of experimental methods and specimens that may be investigated is severely restricted in a large number of state-of-the-art setups. Here, an alternative approach involving HNPs and UCNPs, respectively, is presented providing an overview from their synthesis to optical characterization and to potential fields of application. Based on their inherent flexibility based on their nonlinear optical response, especially in terms of wavelength and intensity tunability, the PMC alleviates prevalent limitations by dynamically adapting the setup to a sample instead of the preliminary culling to a reduced number of eligible specimens that must not change their optical properties significantly during investigation. The use of HNPs supersedes such concerns due to their nearly instantaneously generated, strongly anti-Stokes shifted, coherent emission capable of producing radiation throughout the visible spectral range, including infrared and ultraviolet wavelengths. This way, HNPs transcend the traditional field of imaging and introduces potential applications in optomanipulation or holographic techniques. Thorough (nonlinear) optical characterization of UCNPs and alkali niobate HNP ensembles is performed to assess the fundamental physical mechanisms interwoven with numerical studies leading to their wide-ranging applicability. Final remarks show that HNPs are ideal candidates for realization of the PMC and yet hold an even further potential beyond current prospects. Nonlinear Optics Ultrafast Physics Harmonic Nanoparticles Upconversion Nanoparticles Spectroscopy Harmonic Generation Luminescence LiNbO3 33.07 - Spektroskopie 33.18 - Optik 33.38 - Quantenoptik, nichtlineare Optik 33.79 - Kondensierte Materie: Sonstiges 81.07.Wx - Nanopowders ddc:530
53	Structural and optical impact of transition metal implantation into zinc oxide single crystals and nanowires / Strukturelle und optische Auswirkungen derÜbergangsmetallimplantation in ZnO Einkristalle und Nanodrähte Müller, Sven 30 March 2009 (has links) No description available. 530 Physik Mathematics and Computer Science Nanodraht Zinkoxid Photolumineszenz Kathodolumineszenz Ionenimplantation Leuchtzentren Dotierung Übergangsmetalle Eisen Nickel Mangan Kobalt Vanadium interstitieller Sauerstoff interstitielles Zink grünes Lumineszenzband rot-gelbes Lumineszenzband intra-3d Lumineszenz Zweiphasen Raman Röntgenbeugung nanowire zinc oxide photoluminescence cathodoluminescence ion implantation color center doping transition metals iron nickel manganese cobalt vanadium interstitial oxygen interstitial zinc green luminescence band red-yellow luminescence band intra-3d-shell luminescence secondary phases raman X-ray diffraction 33.07 33.61 33.72 RVC 520: Gitterschwingungen RVQ 000: Halbleiter {Physik}
54	Lanthanide Doped Wide Band Gap Semiconductors: Intra-4f Luminescence and Lattice Location Studies / Lanthanid-dotierte Halbleiter mit großer Bandlücke: Intra-4f Lumineszenz- und Gitterplatzuntersuchungen Vetter, Ulrich 15 July 2003 (has links) No description available. Mathematics and Computer Science Lanthanide Kathodoluminesznez intra-4f Elektronenübergänge Europium Thulium Gadolinium Halbleiter mit großer Bandlücke Aluminiumnitrid kubisches Bornitrid Siliziumkarbid Diamant dünne Schichten tetraedrischer amorpher Kohlenstoff Lichtemitter Starkniveau-Spektroskopie Kristallfeldanalyse Kathodolumineszenz Energiematrix Judd-Ofelt-Theorie Ionenimplantation massenselektierte Ionenstrahldeposition Emissionschanneling Gitterplatz Mössbauerspektroskopie radioaktive Lanthanidisotope 530 Physik lanthanides cathodoluminescence intra-4f electron transitions europium thulium gadolinium wide band gap semiconductors aluminum nitride cubic boron nitride silicon carbide diamond thin films tetrahedral amorphous carbon light emitters Stark level spectroscopy crystal field analysis energy matrix Judd-Ofelt theory ion implantation mass-selected ion beam deposition emission channeling lattice location Mössbauer spectroscopy radioactive lanthanide isotopes 33.60 33.30 33.07 33.06 33.43 33.72 RTF 400: Ionenimplantation {Physik} RTG 400: Anregung von Atomen atomare Energiezustände {Atomphysik} RRJ 000: Emissions- Absorptionsspektroskopie {Physik} RVQ 000: Halbleiter {Physik}

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