X-ray fluorescence emission following K capture and 1s photoionization of Mn and Fe in various chemical environment

An investigation of the Mn and Fe K fluorescence emission in various chemical environments was carried out in the framework of this thesis. A crystal array spectrometer employing four to eight analyzer crystals was built and its spectral and focal properties were examined. Two modes of 1s vacancy creation - photoionization and radioactive electron capture decay from the K shell (K capture) - were used to study the valence shell perturbation due to 1s core hole creation. Multiple excitations in the intermediate and final states are discussed with respect to a comparison of the two modes of excitation. It was found that the K fluorescence after photoionization is influenced by shake transitions, i.e. the valence electrons relax non-adiabatically after the core hole creation. The K capture spectra, in contrast, show considerably less perturbation of the valence shell and therefore provide information about the valence electron configuration that approximately corresponds to the ground state configuration. Concerning the influence of the chemical environment on the K fluorescence it was found that the Kα1 linewidth and the Kβ1,3 center of gravity energy show a dependence on the valence shell net spin. Ligand field multiplet calculations including configuration interaction on the basis of ligand-to-metal charge transfer were carried out to model the spectra that have a core hole in the final state. The exchange interaction between the core hole and the spin-unpaired valence electrons can explain the observed chemical dependence. Studies on Ni support this interpretation. The spectra that result from transitions of the valence electrons to the metal 1s shell (Kβ satellite lines) were interpreted using density functional theories. A rough quantitative agreement between theory and experiment could be achieved within a one-electron, sudden approximation picture for a molecular Mn-nitrido complex. The Kβ satellite spectra are dominated by dipole transitions. (orig.)