Sökning: "Atomic structure"

Visar resultat 11 - 15 av 656 avhandlingar innehållade orden Atomic structure.

  1. 11. Computational Atomic Structure: Applications to Astrophysics and Nuclear Structure

    Författare :Asimina Papoulia; Matematisk fysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : This thesis deals with the modelling of atoms and ions. In heavy systems, where the effect of the nuclear size must be considered, a fully relativistic treatment based on the Dirac-Coulomb Hamiltonian is needed. LÄS MER

  3. 12. Insights into Materials Properties from Ab Initio Theory : Diffusion, Adsorption, Catalysis & Structure

    Författare :Andreas Blomqvist; Rajeev Ahuja; Christopher Wolverton; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Density functional theory; Molecular dynamics; Diffusion; Catalysis; Adsorption; Random structure search; Hydrogen-storage materials; Phase-change materials; Defects and diffusion; Defekter och diffusion; Surfaces and interfaces; Ytor och mellanytor; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

    Sammanfattning : In this thesis, density functional theory (DFT) calculations and DFT based ab initio molecular dynamics simulations have been employed in order to gain insights into materials properties like diffusion, adsorption, catalysis, and structure. In transition metals, absorbed hydrogen atoms self-trap due to localization of metal d-electrons. LÄS MER

  4. 13. Order and interfaces in epitaxial heterostructures : Structure and magnetism

    Författare :Anna L. Ravensburg; Vassilios Kapaklis; Björgvin Hjörvarsson; Gunnar K. Pálsson; Martina Müller; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : The work in this dissertation is devoted to investigating order and interfaces in epitaxial heterostructures. To achieve that the software tool box GenL was developed for simulating and fitting x-ray diffraction patterns from epitaxial thin films, which is used to access structural information on the length scales of interfaces and atomic bonds. LÄS MER

  5. 14. Spectroscopic Investigations of Highly Charged Tungsten Ions - Atomic Spectroscopy and Fusion Plasma Diagnostics

    Författare :Joel Clementson; Atomfysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; extreme ultraviolet spectra; spheromak; electron beam ion trap; magnetic fusion; tungsten; highly charged ions; atomic structure; x-ray spectroscopy; plasma diagnostics; Fysicumarkivet A:2010:Clementson;

    Sammanfattning : The spectra of highly charged tungsten ions have been investigated using x-ray and extreme ultraviolet spectroscopy. These heavy ions are of interest in relativistic atomic structure theory, where high-precision wavelength measurements benchmark theoretical approaches, and in magnetic fusion research, where the ions may serve to diagnose high-temperature plasmas. LÄS MER

  7. 15. X-ray Absorption Spectroscopy on Nano-Magnet Arrays and Thin Films : Magnetism and Structure

    Författare :Andreas Persson; Dimitri Arvanitis; Cormac McGuinness; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; self organization; nano-magnet; xmcd; exafs; peem; magnetism; Surfaces and interfaces; Ytor och mellanytor; Magnetism; Magnetism; Materiefysik; Physics of Matter;

    Sammanfattning : The magnetic and structural properties of nano magnet arrays and ferromagnetic thin films are investigated. Circular x-rays are used and extensive use is made in this Thesis of the X-ray Magnetic Circular Dichroism (XMCD) technique. By means of the XMCD magneto-optic sum rules the values of the orbital and spin moments are determined. LÄS MER