Soft X-ray spectroscopy of porous silicon and potassium halides

We showed that soft X-ray absorption and emission spectroscopy are excellent tools to study the electronic structure of broad band materials. In SXA and SXE the local partial density of states of the unoccupied conduction band and the occupied valence band are mapped, respectively. We applied the methods to porous silicon, a material of enormous interest: for basic science it is of interest because quantum confinement effects can easily be studied, for industry purposes it is the potential of developing optoelectronic materials on the base of silicon that explains the world wide interest at pSi. In the second part of this diploma thesis we applied SXA and SXE spectroscopy to narrow band materials and studied the excitation dynamics and correlation effects. We used core-to-core emission transitions to study the K 3s"-"13d configuration in KF and KI that cannot be reached in absorption processes alone due to the dipole selection rules. We found that the 3d electron is excitonically bound to the 3s core hole and determined the binding energies of the various excitonic states, the exchange splittings, and the crystal field splittings. The importance of the spin-orbit interaction in the 2p"-"13d states manifests itself in the intensity ratio of transitions into final singlet states vs. transitions into final triplet states, that cannot be reached in purely LS-coupled systems. (orig.)96 refs.SIGLEAvailable from TIB Hannover: RA 831(3064) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman