beta-NMR Experimente an adsorbierten 8Li unter Verwendung eines Linux basierten Echtzeit-Datenaufnahmesystems

Im Rahmen der vorliegenden Arbeit wurden beta-NMR Experimente an adsorbierten 8Li auf zwei unterschiedlichen Oberflächen durchgeführt. Dabei gliedert sich die Dissertation im Wesentlichen in vier Teilbereiche: 1. Einer Beschreibung der Apparatur, an der die Experimente durchgeführt wurden. 2....

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Bibliographic Details
Main Author: Kühlert, Oliver
Contributors: D. Fick (Thesis advisor)
Format: Doctoral Thesis
Published: Philipps-Universität Marburg 2003
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Within the scope of this thesis beta-NMR experiments were performed with 8Li adsorbed on two different surfaces. The dissertation consists of four major parts: 1. a descriptions of the used equipment. 2. due to deficiency concerning the existing data recording system a new one has been designed and implemented. It is based on a realtime capable variant of the Linux operating system and uses the framework "ROOT" (cernlib) for data presentation and analysis. In this thesis the basic architecture of the new system will be discussed. A more detailed description of the realtime processes will be given for a special measurement method: Temperature Programmed Desorption (TPD). 3. beta-NMR Experiments at two opponent directions of polarization were performed on 8Li adsorbed on the hydrogen terminated silicium(111) surface. The frequency shift between the resonance curves acquired by the measurements with two opponent polarisations is near 0. Therefore the components of the static electrical field gradient of the lithium binding electron at the nucleus must be 0, too. By means of a simple point charge model it will be proven, that the adsorbed lithium atom binds to the silicium atoms of the crystal and not to the hydrogen atoms. 4. the last chapter introduces models for the diffusion of 8Li on a smooth ruthenium surface and expands the theory on stepped surfaces with a distinct density of steps. Measurements with the R(001)- and Ru(109) surfaces were performed, but the interpretation is disputable due to major impurities by carbon monoxide molecules.