Anisotropy-controlled topological stability of discrete vortex solitons in optically induced photonic lattices

We realize an experimental control over the topological stability of three-lobe discrete vortex solitons by modifying the symmetry of a hexagonal photonic lattice optically induced in a photorefractive crystal. By continuously deforming the lattice wave in one transverse direction, we manipulate the coupling between lattice sites and induce or inhibit the reversal of soliton vorticity

Status of the crystallography beamlines at PETRA III

Since 2013, three beamlines for macromolecular crystallography are available to users at the third-generation synchrotron PETRA III in Hamburg: P11, P13 and P14, the latter two operated by EMBL. Beamline P11 is operated by DESY and is equipped with a Pilatus 6M detector. Together with the photon flux of $2×10^{13}$ ph/s provided by the very brilliant X-ray source of PETRA III, a full data set can be typically collected in less than 2min. P11 provides state-of-the-art microfocusing capabilities with beam sizes down to 1×1 $\mu$ $m^{2}$, which makes the beamline ideally suited for investigation of microcrystals and serial crystallography experiments. An automatic sample changer allows fast sample exchange in less than 20s, which enables high-throughput crystallography and fast crystal screening. For sample preparation, an S2 biosafety laboratory is available in close proximity to the beamline

Observation of double-charge discrete vortex solitons in hexagonal photonic lattices

We report on the experimental observation of stable double-charge discrete vortex solitons generated in hexagonal photonic lattices created optically in self-focusing nonlinear media and show that single-charge vortex solitons are unstable in analogous conditions. Subsequently, we study, both theoretically and experimentally, the existence and stability of spatial vortex solitons in two-dimensional hexagonal photonic lattices. We demonstrate that the stability of the double-charge vortices is a consequence of the intersite power exchange in the vortex soliton, and we provide a simple stability criterion on the basis of the analysis of the corresponding discrete nonlinear model. We extend our analysis to the case of defocusing nonlinearity and show the inversion of the vortex stability properties resulting in the fact that single-charge vortices become stable while their double-charge counterparts are unstable

Time-resolved pump and probe x-ray absorption fine structure spectroscopy at beamline P11 at PETRA III

We report about the development and implementation of a new setup for time-resolved X-ray absorption fine structure spectroscopy at beamline P11 utilizing the outstanding source properties of the low-emittance PETRA III synchrotron storage ring in Hamburg. Using a high intensity micrometer-sized X-ray beam in combination with two positional feedback systems, measurements were performed on the transition metal complex fac-Tris[2-phenylpyridinato-C2,N]iridium(III) also referred to as fac-Ir(ppy)3. This compound is a representative of the phosphorescent iridium(III) complexes, which play an important role in organic light emitting diode (OLED) technology. The experiment could directly prove the anticipated photoinduced charge transfer reaction. Our results further reveal that the temporal resolution of the experiment is limited by the PETRA III X-ray bunch length of ∼103 ps full width at half maximum (FWHM)

Transferring the entatic-state principle to copper photochemistry

The entatic state denotes a distorted coordination geometry of a complex from its typical arrangement that generates an improvement to its function. The entatic-state principle has been observed to apply to copper electron-transfer proteins and it results in a lowering of the reorganization energy of the electron-transfer process. It is thus crucial for a multitude of biochemical processes, but its importance to photoactive complexes is unexplored. Here we study a copper complex—with a specifically designed constraining ligand geometry—that exhibits metal-to-ligand charge-transfer state lifetimes that are very short. The guanidine–quinoline ligand used here acts on the bis(chelated) copper(I) centre, allowing only small structural changes after photoexcitation that result in very fast structural dynamics. The data were collected using a multimethod approach that featured time-resolved ultraviolet–visible, infrared and X-ray absorption and optical emission spectroscopy. Through supporting density functional calculations, we deliver a detailed picture of the structural dynamics in the picosecond-to-nanosecond time range

The Karabo distributed control system

The Karabo distributed control system has been developed to address the challenging requirements of the European X-ray Free Electron Laser facility, including complex and custom-made hardware, high data rates and volumes, and close integration of data analysis for distributed processing and rapid feedback. Karabo is a pluggable, distributed application management system forming a supervisory control and data acquisition environment as part of a distributed control system. Karabo provides integrated control of hardware, monitoring, data acquisition and data analysis on distributed hardware, allowing rapid control feedback based on complex algorithms. Services exist for access control, data logging, configuration management and situational awareness through alarm indicators. The flexible framework enables quick response to the changing requirements in control and analysis, and provides an efficient environment for development, and a single interface to make all changes immediately available to operators and experimentalists

The Karabo distributed control system

The Karabo distributed control system has been developed to address the challenging requirements of the European X-ray Free Electron Laser facility, including complex and custom-made hardware, high data rates and volumes, and close integration of data analysis for distributed processing and rapid feedback. Karabo is a pluggable, distributed application management system forming a supervisory control and data acquisition environment as part of a distributed control system. Karabo provides integrated control of hardware, monitoring, data acquisition and data analysis on distributed hardware, allowing rapid control feedback based on complex algorithms. Services exist for access control, data logging, configuration management and situational awareness through alarm indicators. The flexible framework enables quick response to the changing requirements in control and analysis, and provides an efficient environment for development, and a single interface to make all changes immediately available to operators and experimentalists.</p