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Last Updated: | 31 MAR 2003 |
| Content Owner: | L. Dunn | |
| Page Editor: | L. Dunn |
**** **** **** * * * * * * **** **** **** * * * * * * **** **** * * **** HEADLINES - a digital monthly publication
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Contents of this Issue:
1. Science Highlight - A New Look at
Biological Electron Transfer: Electronic Relaxation in Rubredoxins
(contact: Edward Solomon, Stanford University;
Pierre Kennepohl, University of
British Columbia, Canada)
Electron transfer, the process of moving an electron from one place to another, is vital to almost all chemical systems. It is a fundamental process in organic synthesis, in catalysis, and in the biochemistry of all living organisms. In biological systems, transition metal centers (such as iron and copper) often play the central role in an electron transfer protein, shuttling electrons within or between proteins. Electron transfer proteins are specially designed to do their jobs in a fast and efficient manner, and are often more efficient then any man-made counterparts. Hence, understanding biological electron transfer provides important insight not only into biological mechanisms, but also to a fundamental process of all chemical systems.
Photoelectron spectroscopy (PES) experiments conducted at SSRL have enabled
researchers at Stanford University to gain fundamental insight into the changes
that occur in small molecule model systems of the protein rubredoxin upon
removal of an electron. These studies indicate that the electron transfer
process is more complicated than the "one-electron" model that is often
assumed. Rather, these studies show that there is a large change in the
electronic structure upon removal of an electron. This change in electronic
structure distributes the removal of the electron over a larger volume, thus
decreasing the energy required to remove an electron and allowing the process
to happen more quickly. Hence, these studies provide insight into the factors
which allow electron transfer proteins to efficiently and effectively carry out
their jobs. For more information on this work see:
http://www-ssrl.slac.stanford.edu/research/highlights_archive/electransfer.html
or http://www-ssrl.slac.stanford.edu/research/highlights_archive/electransfer.pdf
2. SPPS Completes First Running Period
(contacts:
Jerry Hastings, SSRL;
John Arthur, SSRL)
The Sub-Picosecond Pulse Source (SPPS) experiment has just finished its first successful running period at SLAC. The SPPS is an international collaboration including SLAC/SSRL, DESY, Uppsala University (Sweden), University of Copenhagen (Denmark), the University of Michigan, the Advanced Photon Source, BioCARS, the University of California at Berkeley, and the National Synchrotron Light Source. SPPS is also supported by the U.S. DOE Office of Basic Energy Sciences. The collaboration has constructed an ultrashort x-ray photon source based on ultrashort electron pulses (~80 fs FWHM) produced by the SLAC Linac. With electron energy of 28.5 GeV, an undulator with period of 8.5 cm produces first harmonic x-rays in the 8-10 keV range. About 30 scientists from collaborating institutions directly participated in the first SPPS run.
The primary goals for the initial run were to test the operation of the new SPPS x-ray beam line, to measure x-ray pulse parameters, to evaluate the synchronization of the new ultrafast laser system with the x-ray pulses, and to measure the scattered x-ray intensity from a variety of samples. The measured x-ray intensity, 2 x 10^7 photons per pulse, agrees well with predictions. Measurement of the electron beam pulse length prior to the final stage of compression in the FFTB tunnel demonstrated a pulse length of the expected ~300 fs. Measurements of the final x-ray pulse width deriving from the final compressed electron beam are planned for the next run. The short-term synchronization between laser and x-ray pulses was found to be quite good, with jitter of less than 2 ps over time frames of 10-50 sec. The x-ray scattering power and background rates for single crystal, powder, and liquid samples were measured and feasibility for pump-probe experiments was established.
Enhancements to the laser system and x-ray beam line will be made during the next few months, in anticipation of the next running period starting November 15. The SPPS will operate in a time shared mode with other experiments in accelerator and high energy physics until 2006, when it will be displaced by the construction of a much more powerful ultrafast x-ray source, the LCLS x-ray free-electron laser.
To view the latest on SPPS visit: http://www-ssrl.slac.stanford.edu/jhhome.html
3. DOE Lehman Review Approves Long-Lead LCLS Procurements in FY2005
(contact:
John Galayda, SSRL)
The second major review of the Linac Coherent Light Source Project took place in Rockville, MD, May 21-23, 2003. The review confirmed that the LCLS is prepared to carry out its plans to make $30M in major acquisitions in fiscal year 2005.
The review addressed the LCLS plan to place a group of "long-lead procurements", proposed for FY2005. The list includes:
The review recommended without reservation that the LCLS should proceed with these acquisitions. This strong endorsement clears the way for approval of "Critical Decision - 2A" authorization of FY2005 funding by the Office of Science - most likely before the end of June. The approval of "long-lead procurements" in FY2005 also makes it possible to begin commissioning the free electron laser early in FY2008, the last year of the LCLS construction project.
4. Funding Approved for a New Soft X-ray
Undulator Beam Line Covering the 250-3000 eV Photon Energy Range
(contact: Jo Stöhr, SSRL)
DOE announced that it will fund the proposal for a new soft x-ray beam line (Beam Line 12) at SSRL submitted by a group of scientists from SSRL and Stanford University under the leadership of Jo Stöhr. This will provide SSRL with a new general user beam line covering the photon energy range from 250-3000 eV. The extended photon energy range will enable access to the K-edges of the light elements carbon, nitrogen and oxygen together with the K-edges of sodium, magnesium, aluminum, silicon, phosphor, sulfur and chlorine within a single experiment. The x-ray source will be an in-vacuum elliptical polarization undulator with unsurpassed brightness and complete polarization control. A plane grating monochromator will provide state-of-the-art spectral resolution over the whole energy range. There will be three branch lines, one of which will be reserved for interchangeable general use chambers. The other two will have permanent end stations for high-energy resolution spectroscopy and high-spatial resolution microscopy, with an emphasis on spatially resolved spectroscopy. It is anticipated that the beam line development project will extend over a period of about 3 years.
5. Director's Materials Science
Review/PRP Meeting - June 9-10
(contacts: Keith Hodgson, SSRL;
Jo Stöhr, SSRL)
A Director's Review of Opportunities with SPEAR3 exploring possible new initiatives in SSRL's chemical and materials science program took place on Monday, June 9, 2003. Chaired by Sunil Sinha (UCSD) and Russ Chianelli (UTEP), the panel included Franz Himpsel (Univ. of Wisconsin), Bennett Larson (ORNL), Simon Mochrie (Yale Univ.), Cyrus Safinya (UCSB), Sarah Tolbert (UCLA) and Don Weidner (SUNY).
The panel was charged with evaluating several proposed initiatives based on the increased performance of SPEAR3. The initiatives were presented by SSRL staff scientists and were evaluated based on their scientific and technical merit, their anticipated value to the SSRL user community, and their link to other new SSRL facilities such as SPPS and eventually the LCLS. The panel supported proposed initiatives based on soft and hard x-ray microscopy and the development of capabilities in x-ray inelastic scattering with sub-eV energy resolution.
The Director's Review segued into a Proposal Review Panel meeting the following day in which Russ, Franz and Sarah were joined by other PRP members Ninian Blackburn (Oregon Graduate Inst.), Torgny Gustafsson (Rutgers Univ.), Chris Hill (Univ. of Utah), Michel Koch (EMBL) and Ron Stenkamp (Univ. of Washington) to formally comment on the results of the Director's review and advise SSRL on strategic issues related to LCLS, SPPS, beam line development and structural biology, among others. The PRP strongly endorsed the recommendations of the Director's Review Committee.
6. Arthur Bienenstock Named Vice Provost and Dean
of Research and Graduate Policy at Stanford University
Arthur Bienenstock, former director of SSRL and current chair of the Materials Council and the Director of the Geballe Laboratory for Advanced Materials, has been appointed by Stanford President John Hennessy to the position of Vice Provost and Dean of Research and Graduate Policy effective September 1, 2003.
Artie will serve on Stanford University's executive cabinet and advise President Hennessy and Provost John Etchemendy on a wide range of issues related to research and graduate education. Hennessy said that Bienenstock, who also recently served as Associate Director of the Office of Science and Technology in the Executive Office of the President, fit the job description perfectly. "This position calls for a combination of intellectual depth, first-rate research skills, thorough knowledge of Stanford and experience dealing with the federal government...Stanford is extremely fortunate to have a person like Professor Bienenstock, who brings together all of these traits in one dynamic individual."
For the full story see: http://news-service.stanford.edu/news/2003/june18/bienenstock-618.html
7. SMB Summer School Coming Up in September
(contacts: Hiro Tsuruta; Serena George; Ana Gonzalez)
SSRL will hold a Structural Molecular Biology Summer School during the period of September 16-19, 2003. The course will highlight the use and applications of three synchrotron x-ray techniques in studying biological systems: Small Angle X-ray Scattering (SAXS), X-ray Absorption Spectroscopy (XAS) and Macromolecular Crystallography (MC). Presentations from experts in the fields will be aimed at the graduate student level, but will also be appropriate for more experienced researchers entering the field. Lectures will be followed by practical sessions giving participants the opportunity to learn data collection and analysis techniques first hand.
The lectures and practical sessions will be held at facilities on the SLAC site and a block of rooms has been reserved at the new SLAC Guest House for participants. Enrollment will be limited so prospective participants should apply before the July 14 deadline. For more course information and to apply see: http://smb.slac.stanford.edu/SR-School/SMB2003/
8. SPEAR3 Project Moving Forward on Fast
Track
contact: Tom Elioff
After the successful removal of SPEAR2 hardware in April, the contract for constructing new heavy duty concrete floors for the ring tunnel and the power supply building were begun. The floor for the power supply building was successfully completed in mid-May and the tunnel floor was completed in mid-June --one week ahead of schedule. The seismic retrofit of the power supply building has begun. The task of establishing new survey and alignment monuments in the tunnel was also initiated ahead of schedule. The contracts for tunnel anchor bolts, magnet raft support plates, cable tray supports within the power supply building, and installation of signal and power cables were awarded this month. This completes the award of all major contracts for SPEAR3. Design and production of technical systems for power supplies, beam line front-ends, cable plant, and RF systems was also completed this month in preparation for installation. Some work remains in magnet raft assembly, vacuum system components, and LCW/HCW systems. SPEAR3 installation remains on track for ring lockup at the end of October and beginning of systems checkout to follow in early November.
9. SSRL SAXS Users Utilize Beam Time at the
Photon Factory
(contacts: Hiro Tsuruta)
As part of a collaborative agreement between SSRL and the Institute of Materials Structure Science, four users and staff from SSRL visited the Photon Factory (PF) in Tsukuba, Japan from May 13-19, 2003. During this beam time on BL-15A, several experiments were conducted, aimed at studying RNA/protein folding, virus maturation and protein-nucleic acid interactions. The SSRL users expressed a high level of satisfaction about their PF experience. SSRL wishes to acknowledge the Photon Factory staff and the PF user groups for agreeing to share their facility in order to accommodate the SSRL users during the SPEAR3 installation shutdown. We thank Profs. Matsushita (PF Director) and Wakabayashi (Osaka Univ.) for their decision to accept SSRL users and Ms. Yoshimi Takahashi (PF) for her administrative assistance. Additional exchanges of beam time between SSRL and the Photon Factory will be arranged in the future as part of this collaborative agreement.
10. SLAC Guest House Now Open for
Business
The new SLAC Guest House 112-room facility opened with an official ribbon
cutting on June 19. The Guest House provides very cost effective lodging
accommodations for users, visitors, and individuals affiliated with the
SLAC/SSRL and Stanford University. The new Guest House is located in excellent
proximity to SSRL. For reservations and more information, please
visit http://slacguesthouse.stanford.edu.
SSRL Headlines is published electronically monthly to inform SSRL users, sponsors and other interested people about happenings at SSRL. SSRL is a national synchrotron user facility operated by Stanford University for the U.S. Department of Energy Office of Basic Energy Sciences. Additional support for the structural biology program is provided by the DOE Office of Biological and Environmental Research, the NIH National Center for Research Resources and the NIH Institute for General Medical S ciences. Additional information about SSRL and its operation and schedules is available from the SSRL WWW site.
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