The complete atomic structure of a five-monolayer film of ${\mathrm{LaAlO}}_3$ on ${\mathrm{SrTiO}}_3$ has been determined for the first time by surface x-ray diffraction in conjunction with the coherent Bragg rod analysis phase-retrieval method and further structural refinement. Cationic mixing at the interface results in dilatory distortions and the formation of metallic ${\mathrm{La}}_{1-x}{\mathrm{Sr}}_x{\mathrm{TiO}}_3$. By invoking electrostatic potential minimization, the ratio of ${\mathrm{Ti}}^{4+}/{\mathrm{Ti}}^{3+}$ across the interface was determined, from which the lattice dilation could be quantitatively explained using ionic radii considerations. The correctness of this model is supported by density functional theory calculations. Thus, the formation of a quasi-two-dimensional electron gas in this system is explained, based on structural considerations.

PILATUS is a silicon hybrid pixel detector system, operating in single-photon-counting mode, that has been developed at the Paul Scherrer Institut for the needs of macromolecular crystallography at the Swiss Light Source (SLS). A calibrated PILATUS module has been characterized with monochromatic synchrotron radiation. The influence of charge sharing on the count rate and the overall energy resolution of the detector were investigated. The dead-time of the system was determined using the attenuated direct synchrotron beam. A single module detector was also tested in surface diffraction experiments at the SLS, whereby its performance regarding fluorescence suppression and saturation tolerance were evaluated, and have shown to greatly improve the sensitivity, reliability and speed of surface diffraction data acquisition.

The structure of a single layer of graphene on Ru(0001) has been studied using surface x-ray diffraction. A surprising superstructure containing 1250 carbon atoms has been determined, whereby $25\times 25$ graphene unit cells lie on $23\times 23$ unit cells of Ru. Each supercell contains $2\times 2$ crystallographically inequivalent subcells caused by corrugation. Strong intensity oscillations in the superstructure rods demonstrate that the Ru substrate is also significantly corrugated down to several monolayers and that the bonding between graphene and Ru is strong and cannot be caused by van der Waals bonds. Charge transfer from the Ru substrate to the graphene expands and weakens the C–C bonds, which helps accommodate the in-plane tensile stress. The elucidation of this superstructure provides important information in the potential application of graphene as a template for nanocluster arrays.

Owing to recent developments in CMOS technology, it is now possible to exploit tomographic microscopy at third-generation synchrotron facilities with unprecedented speeds. Despite this rapid technical progress, one crucial limitation for the investigation of realistic dynamic systems has remained: a generally short total acquisition time at high frame rates due to the limited internal memory of available detectors. To address and solve this shortcoming, a new detection and readout system, coined GigaFRoST, has been developed based on a commercial CMOS sensor, acquiring and streaming data continuously at 7.7 GB s⁻¹directly to a dedicated backend server. This architecture allows for dynamic data pre-processing as well as data reduction, an increasingly indispensable step considering the vast amounts of data acquired in typical fast tomographic experiments at synchrotron beamlines (up to several tens of TByte per day of raw data).

Pilatus is a silicon hybrid pixel detector system for detecting X-rays in single photon counting mode. The PILATUS II chip, fabricated in a radiation tolerant design with a standard 0.25 mum CMOS process, was used to construct multichip modules with a size of 84 times 34 mm² comprising 94'965 pixels. All calibrations and characterizations were carried out with monochromatic X-rays from a synchrotron source. In order to set any required threshold above the noise level between 2.14 keV and 22 keV the detector was calibrated with X-rays. An algorithm to adjust thresholds pixel-by-pixel and create trim files based on X-ray flat-field images was developed. The threshold dispersion was reduced from 343 eV to 36 eV by the means of trim files. An electronic noise of 447 eV has been measured. The PILATUS modules are suitable for various X-ray applications such as diffraction and imaging techniques.