Search results for "synchrotron"
showing 10 items of 307 documents
Pressure-Induced Polymerization of Polycyclic Arene-Perfluoroarene Cocrystals: Single Crystal X-ray Diffraction Studies, Reaction Kinetics, and Desig…
2020
Pressure-induced polymerization of aromatic compounds leads to novel materials containing sp3 carbon-bonded networks. The choice of the molecular species and the control of their arrangement in the crystal structures via intermolecular interactions, such as the arene–perfluoroarene interaction, can enable the design of target polymers. We have investigated the crystal structure compression and pressure-induced polymerization reaction kinetics of two polycyclic 1:1 arene–perfluoroarene cocrystals, naphthalene/octafluoronaphthalene (NOFN) and anthracene/octafluoronaphthalene (AOFN), up to 25 and 30 GPa, respectively, using single-crystal synchrotron X-ray diffraction, infrared spectroscopy, a…
Different structural destinations: comparing reactions of [CuBr2(3-Brpy)2] crystals with HBr and HCl gas
2011
Reaction of green crystalline solid trans-[CuBr2(3-Brpy)2] 1 (3-Brpy = 3-bromopyridine) with HBr (aq) vapour yields brown crystalline salt (3-BrpyH)2[CuBr4] 2 with quantitative conversion. Notably 2 adopts a different crystal structure to the three mutually isostructural compounds (3-XpyH)2[CuCl4] (X = Cl, Br) and (3-BrpyH)2[CuBr2Cl2] which result from reaction with HCl. Crystalline product 2 has been characterised by X-ray powder diffraction and its conversion back to 1 at 370–400 K has been followed in situ by synchrotron X-ray powder diffraction. Crystalline 1 and 2 are further notable for the presence of intermolecular C–Br⋯Br–Cu halogen bonds and (only in the case of 2) N–H⋯Br–Cu hydro…
Characterization of oriented protein-ceramic and protein-polymer-composites for cartilage tissue engineering using synchrotron μ-CT
2007
Abstract In this paper we report on the synthesis of three different gelatine based scaffold materials for the reconstruction of articular cartilage defects. The first scaffold design is based on an unmodified, oriented gelatine network, while the second design further comprises an attached inorganic hydroxyapatite layer and the third design includes poly(l-lactide) microspheres as a model material for future drug-release applications. All three scaffold designs were characterized and imaged using synchrotron μ-CT, obtaining a complete volumetric reconstruction of a previously defined sample region. Furthermore, two unmodified scaffolds were cultivated for one week with porcine chondrocytes…
High-resolution spectroscopy of difference and combination bands of SF6 to elucidate the ν3 + ν1 − ν1 and ν3 + ν2 − ν2 hot band structures in the ν3 …
2014
The strong infrared absorption in the ν3 S–F stretching region of sulphur hexafluoride (SF6) near 948 cm−1 makes it a powerful greenhouse gas. Although its present concentration in the atmosphere is very low, it is increasing rapidly, due to industrial pollution. The ground state population of this heavy species is only 32% at room temperature and thus many hot bands are present. Consequently, a reliable remote-sensing spectroscopic detection and monitoring of this species require an accurate modelling of these hot bands. We used two experimental set-ups at the SOLEIL French synchrotron facility to record some difference and combination bands of SF6: (1) a new cryogenic multiple pass cell w…
Fracture Shape and Orientation Contributions to P-Wave Velocity and Anisotropy of Alpine Fault Mylonites
2021
P-wave anisotropy is significant in the mylonitic Alpine Fault shear zone. Mineral- and texture-induced anisotropy are dominant in these rocks but further complicated by the presence of fractures. Electron back-scattered diffraction and synchrotron X-ray microtomography (micro-CT) data are acquired on exhumed schist, protomylonite, mylonite and ultramylonite samples to quantify mineral phases, crystal preferred orientations, microfractures and porosity. The samples are composed of quartz, plagioclase, mica and accessory garnet, and contain 3-5% porosity. Based on the micro-CT data, the representative pore shape has an aspect ratio of 5:2:1. Two numerical models are compared to calculate the…
Multiband variability studies and novel broadband SED modeling of Mrk 501 in 2009
2017
Astronomy and astrophysics 603, A31 (2017). doi:10.1051/0004-6361/201629540
Oxidation-Induced Changes in the ALD-Al2O3/InAs(100) Interface and Control of the Changes for Device Processing
2018
InAs crystals are emerging materials for various devices like radio frequency transistors and infrared sensors. Control of oxidation-induced changes is essential for decreasing amounts of the harmful InAs surface (or interface) defects because it is hard to avoid the energetically favored oxidation of InAs surface parts in device processing. We have characterized atomic-layer-deposition (ALD) grown Al2O3/InAs interfaces, preoxidized differently, with synchrotron hard X-ray photoelectron spectroscopy (HAXPES), low-energy electron diffraction, scanning tunneling microscopy, and time-of-flight elastic recoil detection analysis. The chemical environment and core-level shifts are clarified for w…
Dynamics of Metal Centers Monitored by Nuclear Inelastic Scattering
2005
Nuclear inelastic scattering of synchrotron radiation has been used now since 10 years as a tool for vibrational spectroscopy. This method has turned out especially useful in case of large molecules that contain a M\"ossbauer active metal center. Recent applications to iron-sulfur proteins, to iron(II) spin crossover complexes and to tin-DNA complexes are discussed. Special emphasis is given to the combination of nuclear inelastic scattering and density functional calculations.
Microhydrological Niches in Soils: How Mucilage and EPS Alter the Biophysical Properties of the Rhizosphere and Other Biological Hotspots
2019
Plant roots and bacteria are capable of buffering erratic fluctuations of water content in their local soil environment by releasing a diverse, highly polymeric blend of substances (e.g. extracellular polymeric substances [EPS] and mucilage). Although this concept is well accepted, the physical mechanisms by which EPS and mucilage interact with the soil matrix and determine the soil water dynamics remain unclear. High-resolution X-ray computed tomography revealed that upon drying in porous media, mucilage (from maize [Zea mays L.] roots) and EPS (from intact biocrusts) form filaments and two-dimensional interconnected structures spanning across multiple pores. Unlike water, these mucilage a…
Removal of molecular contamination in low-energy RIBs by the isolation-dissociation-isolation method
2020
Nuclear instruments & methods in physics research / B 463, 324 - 326 (2020). doi:10.1016/j.nimb.2019.04.072