X-ray spectroscopy techniques employing highly brilliant synchrotron radiation generated by the electron storage ring KARA at KIT Campus North provide unique insight into atomic or molecular structures of materials which are of pivotal importance in the context of the nuclear waste disposal safety case, e.g., the speciation of radionuclides like actinides or radioactive fission and activation products in highly active nuclear waste (HAW) matrices. X-ray absorption spectroscopy (XAS) is based on the precise measurement of a sample’s absorption coefficient for monochromatic X-rays. The beam energy is tuned to excite a specific electronic inner shell state of a selected sort of atoms. This resonant excitation results in absorption edges which exhibit a fine structure (XAFS) originating from the local atomic coordination environment and, thus, providing information on electronic (e.g., oxidation states) or bonding characteristics (interatomic distances, type and number of neighboring atoms). KIT-INE operates two experimental stations at the KIT synchrotron source which are licensed to handle samples containing extended amounts of radionuclides (up to one million times the exemption limit), the INE-Beamline (operational since 2005) and the ACT station at the new CAT-ACT wiggler beamline (commissioned in 2016). The focus at the INE-Beamline is placed on conventional XAS measurements in absorption or total yield fluorescence detection mode and the combination of methods, whereas the core experiment at the ACT station - a multi analyzer crystal X-ray emission spectrometer - enables innovative techniques based on high resolution X-ray emission detection (e.g., HR-XANES, RIXS). The X-ray spectroscopy research group assists in house users of the INE-Beamline and ACT facilities in planning and conducting experiments in the frame of INE’s R&D program and provides support to external researchers who can get access to the beamlines in the frame of common projects or cooperation agreements. Additionally, the group manages administrative tasks related to security clearance, sample transport and radiation safety issues. To secure reliable beamline operation, to meet user needs and to exploit limited KARA operation times as synchrotron source at utmost efficiency, maintenance and consequent infrastructure upgrading are mandatory at both beamline facilities. These tasks are as well in the responsibility of the X-ray spectroscopy group.
|Dr. Jörg Rothe||Dr. Kathy Dardenne|
|+49 721 608 24390||+49 721 608 26669|