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Showing 1 to 20 of 36 for “"rare earth ions"”.
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Anisotropic Spin-Lattice Relaxation Times of Trivalent Rare-Earth Ions Inanhydrous Lanthanum-Trichloride
Made available in DSpace on 2015-05-12T21:41:34Z (GMT). No. of bitstreams: 2 license.txt: 4848 bytes, checksum: 96035ab3f5e1c23cc7138a224ce498bd (MD5) 6604241.PDF: 5144692 bytes, checksum: 9d12b7894724c82f96ac0babb4ee2a7a (MD5) Previous issue date: 1965
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Anisotropic spin-lattice relaxation times of trivalent rare earth ions in anhydrous lanthanum trichloride
… performed on samples cqntaining ~ 2 at.% rpre earth doping using pulse-saturation techniques at X-ba~d frequencies. Angular m~asurements at constant temperature and microwave ~requency were made for.,magnetic field orientations between 0° and 90° ~ith respect to the crystal c-axis in""the …
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The impact of ion-host interactions on the 5d-to-4f spectra of lanthanide rare earth ions
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1985.
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UV-written devices in rare-earth doped silica-on-silicon grown by FHD
… the fabrication of all-UV-written devices in rare-earth doped silica-on-silicon to demonstrate the viability of this versatile single step channel definition process for the production of light sources. <br/><br/>The requirements for the glass substrate and the fabrication of waveguiding …
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Magnetism in crystalline rare-earth compounds
… largely due to the complex behaviour of rare-earth ions. The technique of choice is diffraction; shown to pro- vide the most lucid of results in this field of research. Neutron powder diffraction, a well established tool for determining magnetic structures, has been employed in order to …
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Energy exchange processes in erbium-doped fluoride glasses
… interest in cross relaxation processes between ions in rare earth doped glasses and crystals. In particular interest has focused on diode-pumped lasers and optical waveguide amplifiers based on rare earth ions. This thesis is concerned with developing a model, which can explain the population …
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Temperature measurement using rare earth doped fibre fluorescence
… in an ion. When populated the relative number of ions, and hence the intensity of fluorescence from each of the two closely spaced levels, follow a Boltzmann distribution. Measurements of the fluorescence intensity originating from the two levels can therefore be used to determine temperature. The …
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Fabrication and characterization of Phosphate-based planar waveguides activated by Er3+ ions
… phosphate-based planar wave-guides activated by rare earth ions both by sol-gel and RF-sputtering techniques. The objective of this thesis has been to evaluate various methodologies for fab-rication Phosphorous-based planar waveguides. In this context sol-gel and RF-sputtering techniques for …
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Coherent Interactions in Rare-Earth-Ion-Doped Crystals for Applications in Quantum Information Science
This thesis describes investigations of the use of cryogenically cooled rare-earth-ion-doped crystals for quantum information processing and quantum optics. Several aspects of the coherent interaction between light and rare-earth ions in solids are addressed. Quantum information science has given …
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Hydrothermal aging of zeolite-based catalysts
… under simulated FCC regenerator conditions in a laboratory scale fluidized bed. Fresh and steam-aged catalysts were characterized by surface area reduction using the nitrogen BET and t-Plot surface area methods. The surface morphology was apparent from the scanning electron …
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Phosphors and photonic crystals
… UV laser (257 nm) have been studied. The emissions have been assigned to their corresponding energy levels. Differences in the emission spectra of Y2WO6: RE, Y2O2S: RE, Gd2O2S: RE and Y2O3: RE have been attributed to the different site symmetries of the rare earth ions and to the different …
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Optical and structural characterization of crystalline oxides for laser applications
… general interest in the optical properties of rare-earth ions (Re3+) in crystalline oxides with garnet structure. At this purpose, the aim of this study concerns the optical and structural characterization of crystalline oxides for laser application, with the prospective of enhancing efficiency …
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Chromium (III), Titanium (III), and Vanadium (IV) sensitization of rare earth complexes for luminescent solar concentrator applications
High optical concentrations without excess heating in a stationary system can be achieved with a luminescent solar concentrator (LSC). Neodymium (Nd) and ytterbium (Yb) are excellent infrared LSC materials: inexpensive, abundant, efficient, and spectrally well-matched to high-performance silicon …
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Theoretical studies of structural and electronic properties in transition metal oxides
… for La_{0.5}Sr_{1.5}MnO_4, effects of rare earth ion size on the stability of the coherent Jahn-Teller distortions in undoped perovskite manganites, and symmetry-mode-based classical and quantum mechanical formalism of lattice dynamics. The formula based on tight-binding approach for …
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Applications of a three-body potential model and crystal field calculations to the simulation of EU³⁺, Er³⁺ and Yb³⁺ environments in PbO.SiO₂ glass
An investigation of the local environment of rare-earth doped lead silicate glasses, using molecular dynamics simulation techniques and crystal-field theory, is presented. The primary focus of the research was to develop a more realistic potential model to better describe the environment …
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The thermal conductivity of double nitrate crystals below 1 K
… was found to be independent of the particular rare-earth ion which occupied the La site, the concentration of that ion, the thickness of the sample and the condition of its surfaces. The thermal conductivity, measured both in the direction perpendicular to that axis, was observed to vary …
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Comparative of Flammable and Toxic Gas Sensing behavior for Rare-Earth Elements Substituted Cobalt based Spinel Ferrites
… spinel ferrites doped with 4f electron rare-earth ions to be used as flammable gas sensors. These spinel ferrites were fabricated following a glycol hydrothermal chemical-process. Due to their electronic configuration and charge dynamics, they are very sensitive and selective to …
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Spin-lattice relaxation of trivalent praseodymium, terbium, and erbium in anhydrous lanthanum trichloride: Temperature and magnetic field dependence
… relaxation rates of several trivalent rare earth ions, in the temperature range 0.25 - 4.2o K. We analyze these results within the framework of the Kronig-Van Vleck-Orbach theory, the main features of which we derive in a semi-rigorous manner. We used the pulse saturation method, …
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Vanadium interaction with FCC catalysts
… contaminatioil on both commercial and model rare earth ion-exchanged zeolite-Y catalysts. Vanadium contamination was achieved using a standard (Mitchell) method and catalysts were subject to treatment conditions similar to those found in the regenerator part of a fluidised catalytic cracking …
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