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November 2012 issue
International Workshop on Improving Data Quality and Quantity for XAFS Experiments (Q2XAFS2011)
Photon Factory, Tsukuba, Japan, 8-9 December 2011
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An introductory overview to the special issue papers from the Q2XAFS Workshop in this issue of the journal.
Background and methodology of improving the accuracy of XAFS measurement, towards data deposition and development of theory.
A brief review of energy and intensity calibration methods used for X-ray absorption spectroscopy is given.
In this first report from an ad hoc working group on XAS data format standardization, concepts for addressing three XAS data storage needs are presented: a single spectrum interchange format, a hierarchical format for multispectral X-ray experiment, and a relational database format for XAS data libraries.
X-ray-induced photo-chemistry of metal sites within biological molecules is a concern for X-ray absorption spectroscopy, X-ray crystallography and other techniques in which samples are illuminated with X-rays. The effects of X-ray-induced photo-chemistry are reviewed and the methods used to mitigate these in X-ray absorption spectroscopy are outlined.
The Canadian Macromolecular Crystallography Facility beamline 08B1-1 at the Canadian Light Source has added the capability to perform X-ray absorption spectroscopy on crystal samples.
Scientific cases from original works and literature reviews of great interest for both fundamental research and technological applications are presented to support the advantage of complementary information provided by an IR/X-ray simultaneous approach with both probes exploiting synchrotron radiation sources.
Design considerations are presented for a standard EXAFS beamline at a 6 GeV electron energy, 1 nm rad emittance storage ring.
A program is presented to plan photon-in/photon-out experiments including fluorescence-detected X-ray absorption and X-ray emission spectroscopy. Range-extended XAFS, self-absorption and pump-and-probe experiments are discussed.
Advances in the analysis of QEXAFS data are discussed and new QEXAFS data analysis software is introduced.
Detailed information is provided regarding the performance and status of beamline BL8 at the Synchrotron Light Research Institute (Thailand) for X-ray absorption spectroscopy in the photon energy range 1.25–10 keV.
In this article the time-resolved X-ray absorption spectroscopy beamline at the Synchrotron Light Research Institute, Thailand, is described. The description includes an energy-dispersive set-up employed by the beamline and a result from XAS measurements during a thermal treatment in the production of TiO2.
research papers
The complete polarization analysis for both the linear arbitrary polarization and the various ellipticities of an APPLE II undulator using a multilayer-based soft X-ray polarimeter is shown.
A variable ultra-short-pathlength solution cell for XAFS transmission spectroscopy of light elements
An X-ray absorption fine-structure spectroscopy cell that is suitable for solution-phase studies of the light elements in the series from Na+ and Ca2+ is described.
A single-exposure dual-energy-subtraction X-ray imaging technique, utilizing the harmonic content of a monochromated synchrotron X-ray beam, is presented.
The pencil-beam method is used to measure and correct long-wavelength slope errors on both bimorph and mechanical X-ray mirrors under beamline conditions.
A quick-scanning XAFS system, based on EPICS and LabVIEW, was developed at beamline BL14W1 at the Shanghai Synchrotron Radiation Facility. This paper described the whole system, including the equipment implemented on the beamline and the factors related to its performance. The signal-to-noise ratio was studied under different experimental situations.
The critical dose for chemical modification and the onset of negative mode (cross-linking) dose of PMMA were measured for 300 eV soft X-ray exposure. A method to determine detector efficiency was developed based on the onset of negative mode dose.
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The performance of a fast pixel array detector with a grid mask resolution enhancer has been demonstrated for X-ray photon correlation spectroscopy experiments.
Accounting for low-frequency synchrotron X-ray beam position fluctuations for dynamic visualizations
Dynamic sample behaviour is characterized with a time series of normalized X-ray radiographs. Vertical beam fluctuations, likely caused by thermal effects of the incident beam on the monochromator, are tracked and accounted for with a novel technique.
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A high-frame-rate single-photon-counting pixel detector named Eiger and its suitability for X-ray photon correlation spectroscopy are described.
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The point-spread function (PSF) of a powdered-phosphor fiber-optic taper-coupled CCD area detector was measured, and an analytic expression for its functional form proposed. The `tails' of this PSF were shown to be due almost entirely to the fiber-optic taper, with no contribution from the phosphor itself.
A proof-of-principle experiment of a novel harmonics separation optics for synchrotron facilities is presented.
A novel X-ray beam intensity and position monitor based on a thin film of single-crystal diamond Schottky diode for synchrotron radiation applications has been fabricated and tested.
The successful design and performance of a transmission X-ray microscope with X-ray fluorescence mapping capability at a first-generation synchrotron light source is described.
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A fast algorithm for tomographic reconstruction based on the Fourier method is presented. On CPU, it provides an up to 20-fold performance increase compared with filtered back-projection routines with negligible accuracy degradation.
A cryogenic imaging technique has been developed for DEI-enabled measurements at low temperature from 193 K up to room temperature with a deviation of 1 K, which may be a way to make temperature-dependent measurements of physical properties such as density.
In this study it is demonstrated that coupling transmission electron microscopy with synchrotron radiation X-ray fluorescence microscopy can provide new information about copper topography in 1 µm-thick sections from human THP-1 cells and mouse aorta.
X-ray velocimetry is utilised to measure the velocity of whole blood, seeded with a clinically used ultrasound contrast agent, within live carotid arterial tissue from a rat.
beamlines
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The Hard X-ray Nanoprobe Beamline is a precision platform for scanning probe and full-field microscopy with 3–30 keV X-rays. A combination of high-stability X-ray optics and precision motion sensing and control enables detailed studies of the internal features of samples with resolutions approaching 30 nm.
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