Novel micro-reactor flow cell for investigation of model catalysts using in situ grazing-incidence X-ray scattering

The design, fabrication and performance of a novel and highly sensitive micro-reactor device for performing in situ grazing-incidence X-ray scattering experiments of model catalyst systems is presented. The design of the reaction chamber, etched in silicon on insulator (SIO), permits grazing-incidence small-angle X-ray scattering (GISAXS) in transmission through 10 µm-thick entrance and exit windows by using micro-focused beams. An additional thinning of the Pyrex glass reactor lid allows simultaneous acquisition of the grazing-incidence wide-angle X-ray scattering (GIWAXS). In situ experiments at synchrotron facilities are performed utilizing the micro-reactor and a designed transportable gas feed and analysis system. The feasibility of simultaneous in situ GISAXS/GIWAXS experiments in the novel micro-reactor flow cell was confirmed with CO oxidation over mass-selected Ru nanoparticles

Is genealogical research possible in Japan?: Some Issues Regarding Preservation and Use of Personal Information in Japanese Archives (<Special Feature> Workshop "Discovering histories of foreign communities in Japan: Research, archives and special collect

Two new model systems for use within the rapidly developing ultrafast time resolved x-ray scattering techniques have been prepared. Their photoisomerisation from norbornadiene to quadricyclane was found to be a suitable reaction to follow. Simulations of scattering patterns (not included in this report) showed that if heavy atoms are included in these molecular structures, then the transformation can be followed by transient x-ray scattering techniques. Two new bromosubstituted norbornadienes were synthesised and characterised. Absorption spectroscopy showed that the norbornadienes are converted quantitatively to quadricyclanes under UV irradiation. NMR studies showed that the process was fully reversible and that the norbornadienes could be completely recovered even without addition of catalysts. Furthermore, it was shown that the formation of quadricyclane from norbornadiene was unaffected by triplet sensitizers. The two new model systems synthesised thus are strong candidates for use in time resolved x-ray scattering studies both in gas and condensed phases

Ultrafast Structural Dynamics of Photo-Reactions Revealed by Model-Independent X-ray Cross-Correlation Analysis

We applied angular X-ray Cross-Correlation analysis (XCCA) to scattering images from a femtosecond resolution LCLS X-ray free-electron laser (XFEL) pump-probe experiment with solvated PtPOP ([Pt$_2$(P$_2$O$_5$H$_2$)$_4$]$^{4-}$) metal complex molecules. The molecules were pumped with linear polarized laser pulses creating an excited state population with a preferred orientational (alignment) direction. Two time scales of $1.9\pm1.5$ ps and $46\pm10$ ps were revealed by model-independent XCCA, associated with an internal structural changes and rotational dephasing, respectively. Our studies illustrate the potential of XCCA to reveal hidden structural information in a model independent analysis of time evolution of solvated metal complex molecules.Comment: 8 pages, 5 figures, 50 reference

Correction of complex nonlinear signal response from a pixel array detector

The pulsed free-electron laser light sources represent a new challenge to photon area detectors due to the intrinsic spontaneous X-ray photon generation process that makes single-pulse detection necessary. Intensity fluctuations up to 100% between individual pulses lead to high linearity requirements in order to distinguish small signal changes. In real detectors, signal distortions as a function of the intensity distribution on the entire detector can occur. Here a robust method to correct this nonlinear response in an area detector is presented for the case of exposures to similar signals. The method is tested for the case of diffuse scattering from liquids where relevant sub-1% signal changes appear on the same order as artifacts induced by the detector electronics

Molecular scale structure and dynamics at an ionic liquid/electrode interface

The structural arrangement and dynamics of ions near the IL/electrode interface during charging and discharging was studied by a combination of time resolved X-ray reflectivity and impedance spectroscopy.</p