BESSY Research Articles

Enhanced temperature and gas options at BESSY II beamline KMC-2

Enhanced temperature and gas options at BESSY II beamline KMC-2

Linking Simultaneous In Situ WAXS/SAXS/Raman with Raman/ATR/UV–vis Spectroscopy: Comprehensive Insight into the Synthesis of Molybdate Catalyst Precursors

A new setup is presented which enables simultaneous wide- and small-angle X-ray scattering (WAXS/SAXS) and Raman spectroscopic experiments during the synthesis of Mo-based mixed oxide catalyst precursors at the μ-spot beamline at the Berliner Elektronenspeicherring-Gesellschaft fur Synchrotronstrahlung (BESSY). Furthermore, we report about the separate monitoring of the same reactions under comparable conditions by simultaneous combined ATR/UV–vis/Raman spectroscopic measurements. For testing the performance of both experimental setups two syntheses were described comprising the precipitation of metal molybdates by mixing solutions of metal nitrates and ammonium heptamolybdate. Additionally, the effect of H3PO4 admixture on precipitation was investigated. The combined evaluation of spectroscopic and WAXS/SAXS data allows the discrimination between different molybdate species appearing in solution and precipitate. Furthermore, these molybdate species could be assigned to separate phases of different crystallinity.

MODULIGA: The LIGA process as a modular production method-current standardization status in Germany

The LIGA process combines X-ray lithography with electroplating and molding. It is a technique used worldwide for the fabrication of high aspect ratio microstructures. In Germany, this technique will be established as a production line to manufacture micro system devices. A project named (modular production method using the LIGA process) MODULIGA has the goal to link together the activities of the German LIGA centers Forschungszentrum Karlsruhe / Institut fur Mikrostrukturtechnik, Karlsruhe (FZK/IMT), Institut fur Mikrotechnik, Mainz (IMM) and Berliner Elektronenspeicherring-Gesellschaft fur Synchrotronstrahlung, Berlin (BESSY). LIGA process steps will be standardized and interface specifications will be defined to establish a modular production method. Interface specifications are defined for masks, substrate and resist, exposure technology, development and finally electroplating. The standards are defined by testing criteria. The challenges and the current status of standardization will be described.

X-ray response of epitaxial GaAs

We summarize the results of a number of x-ray experiments on an epitaxial GaAs device carried out in both our laboratory and the Physikalisch-Technishe Bundesanstalt radiometry Laboratory at the Berliner Elektronenspeicherring-Gesellschaft fur Synchrotronstrahlung Synchrotron Radiation Source. The detector has a diameter of 1.5 mm and is fully depleted to a depth of 40 μm. It has been characterized as a function of energy, bias, and temperature. At −35 °C we determine the charge collection efficiency to be 97% and find that energy resolutions ranging from 730 to 930 eV full width at half maximum (FWHM) can be readily achieved using conventional pre-amplifiers over the energy range 6–60 keV. By considering the various contributions to the FWHM, we show that leakage current and charge trapping noise dominate the resolution function. From detector modeling we determine the effective electron and hole density/cross section products to be 7 and 3 cm−1, respectively.

BESSY users' meeting

BESSY users' meeting

Surface Physics at BESSY

Surface Physics at BESSY