Showing papers in "Synchrotron Radiation News in 2003"

Ultrafast time‐resolved X‐ray absorption spectroscopy of chemical systems

Abstract: X-ray absorption spectroscopy (XAS) is a well-established technique to probe the electronic and structural properties of a large class of systems, ranging from solid-state materials to proteins [1]. X-ray spectra are characterized by a series of edge features, which arise due to the extraction of a core electron from the inner K, L, M, etc. shells to the ionization limit. Zooming into one of the edges reveals a variety of fine structure near the edge, the so-called XANES or X-ray absorption near edge structure, while at higher energies above the edge the so-called EXAFS or extended X-ray absorption fine structure, can be observed. In many-body systems, these features are caused by the presence of neighboring atoms and lie in the fact that the photoelectron scatters off the neighboring atoms and the backscattered wave interferes with the outgoing wave. This interference gives rise to weak modulations of the otherwise smoothly varying absorption cross-section as a function of Xray energy. The proper analysis of these features delivers information about the local geometric structure to high accuracy. For studying chemical properties, XAS has the following advantages:

Orbit Control at the SLS Storage Ring

Abstract: Precise orbit control is one of the crucial ingredients for stable operation of the SLS storage ring. The orbits are taken by the digital BPM system which allows beam position measurements to the sub-micron level at sampling rates of up to 4 kHz at 72 locations in the ring. Orbits are corrected with respect to a user defined reference by applying SVD techniques and a direct response matrix inversion. A slow global orbit feedback operating at correction rates of up to 1 Hz stabilizes the orbit to within ∼0.5 µm rms at the locations of the insertion devices. Energy drifts are automatically corrected using the RF frequency as an additional corrector, resulting in a long term energy stability of σ(dP/P) ≈ 10 −5 . The status of a digital BPM system based fast orbit feedback running at 4 kHz sampling rate is presented.

Soft x‐ray microscopy at the NSLS

Abstract: TOBIAS BEETZ, MICHAEL FESER, HOLGER FLECKENSTEIN, BENJAMIN HORNBERGER, CHRIS JACOBSEN, JANOS KIRZ, MIRNA LEROTIC, ENJU LIMA, MING LU, 1 DAVID SAYRE, DAVID SHAPIRO, AARON STEIN, D O N TENNANT, AND SUE WIRICK 1 Department of Physics & Astronomy, Stony Brook University, Stony Brook NY 11794, USA 2 Brookhaven National Laboratory, Upton, NY 11973-5000, USA New Jersey Nanotechnology Consortium, 600-700 Mountain Ave, Murray Hill, NJ 07974, USA

The NIGMS structural biology facility at the NSLS

Abstract: With the advent of structural genomics and the post-genomic era, there is an increased demand for synchrotron radiation facilities for macromolecular structural biology [1]. Several of the existing facilities are affiliated in one or more ways with the newly created Centers for Structural Genomics, leaving individual investigators with little to no access to synchrotron radiation. To provide synchrotron access for these small groups, the National Institute of General Medical Sciences (NIGMS) established the X6A facility at the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory. The purpose is to provide synchrotron access to individual macromolecular crystallography groups and to the biological/biochemical and biophysical community at large. It is the X6A mission to assist expert and nonexpert crystallographers and provide training to interested individuals in the areas from protein purification to the determination of the molecular atomic coordinates.

The X‐ray Microscopy and Micro‐spectroscopy facility at the ESRF

Abstract: J. SUSINI, M. SALOMÉ, U. NEUHAEUSLER, O. DHEZ, D. EICHERT, B. FAYARD, A. SOMOGYI, S. BOHIC, P. BLEUET, G. MARTINEZ-CRIADO, R. TUCOULOU, A. SIMIONOVICI, R. BARRETT, AND M. DRAKOPOULOS ID21 beamline, European Synchrotron Radiation Facility, Grenoble, France ID22 beamline, European Synchrotron Radiation Facility, Grenoble, France ID18F beamline, European Synchrotron Radiation Facility, Grenoble, France CNRS, Laboratoire d'Utilisation du Rayonnement Electromagnétique, Orsay, France CNRS, Ecole Normale Supérieure, Lyon, France

TwinMic: Combined scanning and full‐field imaging microscopy with novel contrast mechanisms

Abstract: TwinMic - Combined scanning and full-field imaging microscopy with novel contrast mechanisms

The gas phase photoemission beamline at Elettra

Abstract: This paper reports the present stage of commissioning of the gas-phase photoemission beamline at Elettra, Trieste. The beamline is designed for atomic and molecular science experiments with high-resolution and high-flux synchrotron radiation. It consists of an undulator source, variable-angle spherical-grating monochromator and two experimental stations. The design value of the energy range is 20 to 800 eV with a specified resolving power of over 10000. The procedure adopted for calibration of this type of monochromator is discussed. At present a resolving power up to 20000 and a range up to 900 eV have been measured. Absorption spectra taken at the argon L(II,III)-edge and at the nitrogen, oxygen and neon K-edges are as sharp as, or sharper than, any reported in the literature. The instrumental broadening is well below the natural line-width making it difficult to quantify the resolution; this problem is discussed.

X-ray microscopy at the Advanced Photon Source.

Abstract: X-ray microscopy has experienced tremendous growth at the Advanced Photon Source (APS) since the synchrotron began operations in late 1996. While this burgeoning productivity could be expected at a third-generation, high-energy storage ring such as the APS, ESRF, or SPring-8, the diversity of techniques (Table 1) and applications that have developed in the intermediate {\\-4 keV) and hard (6-30 keV) Xray energy ranges is impressive. Most of these activities are fueled by undulators combined with X-ray focusing optics, although several heavily subscribed programs are active on bending magnet sources. Major advances in hard X-ray Fresnel zone plate (ZP) lenses and Kirkpatrick-Baez (KB) mirrors have driven progress in X-ray microscopy at APS. Mirror optics capable of sub-micron focusing and >70% efficiency are used at several beamlines. Efforts are underway to develop KB mirrors at APS with 100 nm resolution using advanced differential deposition and polishing methods. KB mirrors with better than 400 nm resolution made by differential deposition are now in routine use on beamline 34-ID (Figure la). In parallel, several beamlines have implemented ZP optics. The latest generation of ZPs in use at APS are made of gold, have outer zone widths of 50-110 nm and thicknesses of 0.4-1.3 |im, with diffraction efficiencies of 10-15% at 2-8 keV energies. To obtain higher efficiency, several identical ZPs are stacked within an optical near-field (Figure lb). Fluorescence microscopy, tomography, and microdiffraction are widely used at APS. Applications being pursued at APS Collaborative Access Teams (CATs) and X-ray Operations and Research (XOR) are mostly in the materials, geological, biological/biomedical, and environmental sciences. APS users also take advantage of adjacent optical, atomic force, and electron microscopy facilities. Scanning fluorescence X-ray microscopy (SFXM) and spatially resolved X-ray absorption near-edge structure (micro-XANES) are among the most active areas at APS. Elemental and chemical state information can now be studied with up to attogram sensitivity. Fluorescence microanalysis experiments in the biological, environmental, and geological sciences, in particular, are thriving. Three-dimensional (3D) imaging by X-ray tomography is also popular among users. New modalities are under development, including phase contrast and fluorescence methods at unprecedented sensitivity [Naghedolfeizi 2003]. Extension of diffraction methods to the micron-scale domain and beyond is one of the most rapidly growing subfields at APS. Microdiffraction utilizing KB and ZP

Towards automated data collection at the Stanford Synchrotron Radiation Laboratory

Abstract: The Stanford Synchrotron Radiation Laboratory (SSRL) will experience a significant increase in the brightness of its X-ray beamlines once the SPEAR3 storage ring upgrade is complete in early 2004 [1]. On the protein crystallography beamlines, a high-quality diffraction image will be collected in just seconds, and data sets will be completed in a matter of minutes when the accelerator is run at its final design current. With such powerful experimental stations, the need for fully automated sample changing is essential in order to make efficient use of the facility. In addition, a high-speed crystal screening system will allow users to widen the scope of their experimental goals. The Structure Determination Core of the Joint Center for Structural Genomics (http://www.jcsg.org) and the Structural Molecular Biology group (http://smb.slac.stanford.edu) at SSRL have developed an automated crystal screening environment and data collection facility on beamline 11-1, where it has been operational for approximately 12 months. At the start of the SPEAR3 run, the system will be available to the general user community on four beam lines. The system employs a robotic sample changer and an automated crystal centering algorithm to complete the crystal screening process without human intervention. In order to facilitate the synchronization of experimental information between the home laboratory and the experimental facility, a web interface has been developed that allows users to upload crystal information using an Excel spreadsheet. The automation systems will be installed on two additional beam lines, and thus is soon a standard component on all macromolecular crystallography beam lines at SSRL.

Further development of soft X-ray scanning microscopy with anelliptical undulator at the Advanced Light Source

Abstract: Soft x-ray scanning microscopy (1) is under continuing development at the Advanced Light Source. Significant progress has been made implementing new scan control systems in both operational microscopes (2) and they now operate at beam lines 5.3.2 and 11.0.2 with interferometer servo scanning and stabilization. The interferometer servo loop registers the images on a universal x/y coordinate system and locks the x-ray spot on selected features for spectro-microscopic studies. At the present time zone plates are in use with 35nm outer zone width and the imaging spatial resolution is at the diffraction limit of these lenses. Current research programs are underway in areas of polymer chemistry, environmental chemistry and materials science. A dedicated polymer STXM is in operation on a bend magnet beam line (4) and is the subject of a separate article (3) in this issue. Here we focus on the capabilities of STXM at a new beam line that employs an elliptical undulator (5) to give control of the polarization of the x-ray beam. This facility is in the process of commissioning and some results are available, other capabilities will be developed during the first half of 2003.

SSRL structural molecular biology summer school 2004

Abstract: The eighth Structural Molecular Biology Summer School was held at SSRL from September 8–11, 2009. The school focused on three synchrotron based techniques: macromolecular crystallography, small angle X-ray scattering, and X-ray absorption spectroscopy, and the application of these techniques to biological problems. This year's Summer School was attended by 24 students and was led by a team of 18 tutors (who are internationally recognized experts in their field). It consisted of two days of lectures, followed by a day and a half of rotating practical sessions and a final afternoon comprising a tour of the SSRL facility and a wrap-up question and answer session.

X‐ray microscopy at BESSY

Abstract: After the first X-ray microscopy experiments at DESY in 1976 f 1], a soft X-ray microscope was installed at the ACO-storage ring in Orsay in 1979 [2]. In 1983, an improved version of this microscope was installed at a bending magnet beamline of the BESSY I-storage ring in Berlin in 1983 [3]. In this microscope, working with X-rays at energies between the carbon and oxygen K edges at 284 eV and 534 eV, respectively (the so-called water window), the polychromatic synchrotron radiation is focused onto the object using a holographically made condenser zone plate. Together with a pinhole, the condenser acts as a linear monochromator. An enlarged image of the object is generated by a micro zone plate. Holographically made micro zone plates were used [4,5], which have been replaced by zone plates with higher resolution built by electron beam lithography [6-8]. In a further improved version of this microscope with object holder in air for wet specimens [9], the images have been recorded with a cooled, slow-scan CCD camera [10] with a magnification of about two thousand, typical exposure times of a few seconds, and a spatial resolution of 30 nm.

Workshop on coherent synchrotron radiation in storage rings

Abstract: about the possibility of broadband coherent synchrotron radiation (CSR) as a source of intense radiation in the traditionally difficult far-infrared/terahertz wavelength region. One of the most interesting features of CSR is that the emitted power scales quadratically with the number of electrons involved. Since the typical number of electrons in a bunch is a billion or more, the potential for gain is huge. To discuss recent advances in exploiting this novel source, the Workshop on Coherent Synchrotron Radiation in Storage Rings was held in Napa, California, on October 28–29, 2002. The workshop was sponsored by the Advanced Light Source (ALS) and BESSY-II and was chaired by John Byrd (ALS). The possibility of generating broadband CSR was raised over half a century ago with the advent of the first high-energy electron accelerators. Coherent emission occurs when the length of the electron bunch (or any structure on the bunch) is comparable to the wavelength of the emitted radiation. The longest emitted wavelength is limited by a waveguide cutoff condition determined by the vacuum chamber height and the radiation opening angle and typically is between a few millimeters and few hundred microns in third generation rings. Therefore, bunch lengths less than a few millimeters and vacuum chambers large enough to transmit the radiation are necessary for observing CSR. The first observations of stable CSR in a storage ring, reported at the workshop in presentations by Gode Wustefeld (BESSY-II) and by Peter Kuske (BESSY-II), were achieved via reduction of the bunch length at low currents (~10 μA/bunch) by reducing the lattice momentum compaction and controlling higher order effects with harmonic sextupoles. The BESSY group observed a coherent enhancement at wavelengths as short as a few hundred microns. Fernando Sannibale (ALS) showed that the emission at shorter wavelengths than expected can be explained by a static distortion of the electron bunch due to its interaction with the radiation. However, the gain from the CSR is not unlimited. The interaction of the radiation with the electron beam can also drive a self-amplified instability, resulting in periodic bursts of CSR. Such bursts of far IR synchrotron radiation have been observed at a number of rings. A model of this instability was presented by Gennady Stupakov (Stanford Linear Accelerator Center) and the first experimental results showing agreement of the instability threshold MEETING REPORTS

Indus‐1 and Indus‐2: Indian synchrotron radiation sources

Abstract: (2003). Indus‐1 and Indus‐2: Indian synchrotron radiation sources. Synchrotron Radiation News: Vol. 16, No. 5, pp. 43-48.

Time‐resolved capabilities at the advanced photon source

Abstract: Time-resolved X-ray science is a rapidly advancing multidisciplinary field that has come to fruition through a convergence of exciting scientific opportunities and novel experimental techniques. The Advanced Photon Source (APS) at Argonne National Laboratory (ANL) has a major stake in the development of this field on a number of its sectors or Collaborative Access Teams (CATs) currently pursuing time-dependent X-ray studies. Here we describe some of the research being performed at APS in this area, highlighting activities at the Center for Real-Time X-ray Studies operated by the University of Michigan and Howard University (MHATT) CAT in Sector 7, the Basic Energy Sciences Synchrotron Radiation Center (BESSRC) in Sectors 11 and 12, the Chemistry/Materials Science CARS CAT in Sector 15, and the Pacific Northwest Consortium (PNC) CAT in Sector 20, and the Biology Consortium for Advanced Radiation Sources (CARS) CAT in Sector 14.

Recent developments at the ESRF radiation source

Abstract: Machine parameters The accelerator complex consists of a 200 MeV electron linear accelerator, a 6 GeV booster synchrotron and a 6 GeV storage ring of 844 m circumference. The storage ring magnet lattice is an expanded Double Bend Achromat with distributed dispersion and alternating high and low horizontal p straight sections. Out of the 32 straight sections, 28 can accommodate 5 m long Insertion Devices. In addition a number of bending magnets ports are available for the installation of beamlines. Table 1 presents a summary of the main characteristics and parameters of the electron beam.