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Abstract: Advanced Design Consulting, Inc. (ADC) has designed accurate compact slits for applications where high precision is required. The system consists of vertical and horizontal slit mechanisms, a vacuum vessel which houses them, water cooling lines with vacuum guards connected to the individual blades, stepper motors with linear encoders, limit (home position) switches and electrical connections including internal wiring for a drain current measurement system. The total slit size is adjustable from 0 to 15 mm both vertically and horizontally. Each of the four blades are individually controlled and motorized. In this paper, a summary of the design and Finite Element Analysis of the system are presented.
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Jan 2007
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Optics
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Abstract: The 124 beamline is dedicated to the measurement of diffraction data from micro-crystals of macromolecules. The optical design gives high versatility in selecting the beam size at the sample and at the detector through the use of two pairs of Kirkpatrick-Baez arranged mirrors. The end-station is similarly designed to allow the optimization of the final signal-to-noise ratio of the diffraction measurements. The layout and key properties of the optics and end-station components are presented.
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Jan 2007
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Abstract: Energy dispersive EXAFS (EDE) and diffuse reflectance infrared spectroscopy (DRIFTS) are combined synchronously at high time resolution (17 Hz) to probe how NO(g) reacts with γ-Al2O3 supported, metallic Rh nanoparticles of an average 11 Å diameter; a bent nitrosyl species is considered to be the key to the formation of N2O.
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Jan 2007
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NONE-No attached Diamond beamline
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Abstract: Microprobe EXAFS analysis of lustre decoration from a late 13th century Hispano–Moresque potsherd has been used to examine the metallic oxide to metal ratios in different shaded copper lustre finishes. A single specimen from 13th century Paterna, exhibiting typical red and green colorations, is found to contain different copper/silver ratios depending on the color. EXAFS has been used to determine the local atomic environment of the copper and reveals a corresponding variation in the metal to oxide ratio of the copper content which is related to the visual effect.
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Dec 2006
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Abstract: When Diamond Light Source goes into operation in January 2007, one of the first beamlines will house a state-of-the-art PhotoEmission Electron Microscope (PEEM). On July 12 and 13, 2006, Diamond hosted a workshop to promote the wide-ranging capabilities of PEEM to the user community. An international audience enjoyed talks and discussions on interface magnetism, geological science, surface chemistry and the principles of X-ray excited PEEM.
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Dec 2006
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Health Physics
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Abstract: The European Directive 96/29/Euratom of 13/05/1996, based on the ICRP 60 Recommendations, defines basic safety standards for the protection of the health of workers and the general public against the dangers arising from ionising radiation. Member states of the European Union have had to integrate these basic standards in their national legislation. Synchrotron radiation facilities are affected by this new radiation protection legislation. In the UK, the Daresbury Synchrotron Radiation Source (SRS) operates under the Ionising Radiations Regulations 1999, and the third generation Diamond Light Source (DLS) project is largely benefiting from their experience. In France, the ESRF case is presently being used to define detailed prescriptions, that will also apply to future sources in this country, for example the third generation light source Synchrotron Soleil, presently under construction. This paper summarises general policies and practices of these four SR facilities: SRS, European Synchrotron Radiation Facility (ESRF), DLS and Synchrotron Soleil. (c) 2007 Elsevier Ltd. All rights reserved.
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Dec 2006
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Abstract: The effect of pressure on the crystal structure of salicylaldoxime has been investigated. The ambient- pressure phase (salicylaldoxime-I) consists of pairs of molecules interacting through oximic OH(...)O hydrogen bonds; taken with phenolic OH(...)N intramolecular hydrogen bonds, these dimers form a pseudo-macrocycle bounded by an R(4)(4)(10) motif. The dimers interact principally via pi(...)pi stacking contacts. Salicylaldoxime derivatives are used industrially as selective solvent extractants for copper; the selectivity reflects the compatibility of the metal ion with the pseudo-macrocycle cavity size. On increasing the pressure to 5.28 GPa the size of the cavity was found to decrease by an amount comparable to the difference in hole sizes in the structures of the Cu(2+) salicylaldoximato complex and its Ni(2+) equivalent. On increasing the pressure to 5.93 GPa a new polymorph, salicylaldoxime-II, was obtained in a single-crystal to single-crystal phase transition. PIXEL calculations show that the phase transition is driven in part by relief of intermolecular repulsions in the dimer-forming OH(...)O-bonded ring motif, and the ten-centre hydrogenbonding ring motif of the phase I structure is replaced in phase II by a six-centre ring formed by oximic OH(...)N hydrogen bonds. The transition also relieves repulsions in the pi(...)pi stacking contacts. The intramolecular OH(...)N hydrogen bond of phase I is replaced in phase II by a intermolecular phenolic OH(...)O hydrogen bond, but the total interaction energy of the pairs of molecules connected by this new contact is very slightly repulsive because the electrostatic hydrogen-bond energy is cancelled by the repulsion term. The intra- to intermolecular hydrogen-bond conversion simply promotes efficient packing rather than contributing to the overall lattice energy.
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Dec 2006
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Abstract: Recent thermodynamic and neutron scattering measurements of thin films of normal-alkanes adsorbed on MgO (1 0 0) surfaces are reported. Neutron Diffraction and Neutron Vibrational Spectroscopy data are discussed with reference to a comprehensive set of high-precision volumetric isotherms for the alkanes.
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Nov 2006
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Abstract: Inelastic neutron scattering (INS) studies of the dynamical response of
H2
films adsorbed on MgO (1 0 0) surface are compared to and correlated with structural information from neutron diffraction measurements of equivalent
D2
films. At low coverage, a prominent peak, believed to be the para–ortho transition (usually observed at 14.7 meV in bulk
H2
) is observed at
∼11.2meV
. For film thicknesses between 0.8 and
∼3
layers this peak becomes asymmetric with additional scattering on the high-energy transfer side of the peak. As molecules are added to the third layer we observe the concomitant growth of a peak at 14.7 meV.
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Nov 2006
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Abstract: The crystal structure of VEGF-E was solved by the sulfur single-wavelength anomalous dispersion method (S-SAD) using highly redundant low-resolution data collected at a wavelength of 1.7 Å with an estimated anomalous signal of 1.5%. 11 sulfur sites, nine out of 16 disulfide bonds and two out of 12 methionines could be located in the asymmetric unit using data truncated at a resolution of 4.1 Å; however, none of the common diffraction data-quality indicators for SAD allowed clear discrimination between successful and unsuccessful resolution cutoffs. The high solvent content of 75% allowed efficient density modification to be performed and an unbiased electron-density map of good quality to be generated. This study demonstrates the strength of S-¬SAD for phasing using accurate highly redundant data at low resolution.
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Nov 2006
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