PhD thesis

PhD thesis

PhD thesis

PhD thesis

PhD thesis

PhD thesis

PhD thesis

PhD thesis

PhD thesis

PhD thesis

Neutron Laue diffraction is an important method of neutron scattering for measuring single crystals. Laue diffraction patterns are generated in a matter of seconds from very small crystals i.e. <1mm3. FALCON has two scintillating plate detectors coupled to four iCCD cameras each, to produce a 2D projection of a large volume of reciprocal space in a single Laue pattern. Such images can be used to index complex crystal structures, characterise features such as twinning or...

The instrument is primarily suited for magnetic structure determination under various conditions, which includes magnetic fields up to 17 T, temperatures down to 30 mK and pressures up to 10 kbar. The most common application is to reveal spatial arrangement ordered spin structures. Using the polarized neutrons option facilitates the separation of magnetic contributions from nuclear scattering. The measurement of flipping ratios allows registration of very weak magnetic scattering and the mapping of spin density...

The neutron tomography beam line V7 was designed with two measuring positions: the first one is located directly at the end of the neutron guide, where a very high neutron flux is available but the image resolution is limited due to the beam divergence. The second measuring position uses a pin-hole geometry followed by more than 5m of flight tube in order to gain a high collimation ratio and image resolution. The high-flux measuring position...

Electromagnetic modes of photonic nanostructures can exhibit increased near-field energy densities which can be applied in many fields such as biosensing, quantum dot solar cells or photon upconversion. Optimizing such systems enforces to systematically analyze large amounts of numerically obtained three-dimensional field distribution data, as in the presented dataset. The simulated system is a silicon photonic crystal slab on glass (subspace) with a hexagonal lattice of cylindrical holes. The holes are filled with a medium...

Multi-junction solar cells allow to utilize sunlight more effectively than single junction solar cells. In our work, we present optical simulations of III-V-on-silicon solar cells with a metal grating at the back, which experimentally have reached more than 33% power conversion efficiency. First, we perform simulations with the finite element method and compare them with experimental data to validate our model. We find that accurately modeling the investigated geometrical structure is necessary for best agreement...

The CPMU17_EMIL - Hard x-ray EMIL Beamline uses a planar cryogenic in-vacuum undulator to cover the photon energy range from 700-10000eV. A toroidal mirror M1 collimates (vertically) and focusses (horizontally) the U17 beam, which is then diffracted either by a double crystal monochromator (DCM, with crystal pairs Si 111, Si 311, Si 422 selectable) or passed to a plane grating monochromator (PGM) equipped with two blazed gratings (400 and 800 l/mm). A switching mirror unit...

In the Energy Materials In-situ Laboratory Berlin (EMIL) at the BESSY II synchrotron facility, we have set up an infrastructure that allows x-ray absorption spectroscopic (NEXAFS) studies of energy materials under operating conditions. This setup is based on a three-electrode electrochemical liquid flow-cell attached to an ultra-high vacuum chamber (UHV) dedicated for in-situ/operando studies. To isolate the cell environment containing liquid electrolyte from the UHV of the analysis chamber, a very thin (about 100 nm)...

A crystallographic fragment screening (CFS) has been performed on a spliceosomal yeast protein-protein complex of Aar2 and the RNaseH-like domain of Prp8 (AR). The F2X-Universal Library is a fragment library representing the commercially available chemical space of fragments. 917 fragments have been individually screened via crystal soaking. The datasets that could be successfully auto-processed and auto-refined had been subjected to a Pan-Dataset Density Analysis (PanDDA) (Pearce et al., 2017). This analysis allows to find low...

PhD thesis

The reflectometer V6 allows measuring the neutron optical reflectivities on flat surfaces at grazing angles. The reflectivity is related to the variation of the refractive index within a depth of about 200 nm, thus structural depth profiles can be studied at solid-air, solid-liquid and free liquid surfaces.