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SSRL Headlines Vol. 8, No. 9  March, 2008


Contents of this Issue:

  1. Science Highlight — Novel Ferroelectric Nanostructures for Nanoelectronic Devices
  2. Science Highlight — The Structure of a Reaction Intermediate in Enzymatic Halogenation
  3. Budget Impact on SSRL User Operations
  4. Very Small Spot Size Achieved at the New BL13-2
  5. SSRL School on Synchrotron XAS Techniques in Environmental and Material Sciences
  6. Ultrafast X-ray Summer School, June 17-20, 2008
  7. 2008 SSRL/LCLS Users' Meeting, October 15-18, 2008
  8. Big Science Gets Small: New BL6-2 Microscope

1.  Science Highlight — Novel Ferroelectric Nanostructures for Nanoelectronic Devices
       (contacts: L.E. Fuentes-Cobas, Advanced Materials Research Center)

Experimental 2-D diffraction pattern.
New approaches to the fabrication of ferroelectric nanostructures onto substrates are critical for the development of competitive functional devices that successfully integrate at nanoscale ferroelectrics as alternative materials in the microelectronic industry. These approaches have to meet reliability and utilization requirements to realize a cost-effective production of an increasing demand for ultra-high-density memories or nanometric electromechanical systems. An important challenge in the fabrication of ferroelectric nanomaterials supported onto substrates is the ability to fabricate an organized arrangement of the nanostructures. This is a key point for the applications of ferroelectrics in nanoelectronic devices.

Recently, scientists from the Institute of Materials Science of Madrid (CSIC) and the Centre for the Research of Advanced Materials in Chihuaha, in collaboration with Apurva Mehta of SSRL, used grazing incidence scattering experiments to determine the crystal structure and texture of ferroelectric nanostructures onto SrTiO3 single crystal substrates.

For the preparation of these nanostructures, a novel preparation method was used, which involves the use of microemulsions, sol-gel chemistry and chemical solution deposition. A transparent solution was first prepared by mixing a PbTiO3 precursor sol and a microemulsion formed by water, cyclohexane and the surfactant Brij 30 (Polyoxyethylene(4) lauryl ether). The solution was deposited onto the substrates by spin-coating and dried under controlled conditions. After a rapid thermal treatment of crystallization at 650ºC, nanostructures with uniform sizes of ~40 nm diameter and showing periodicity in some zones of the substrate were obtained.

The analysis of these nanostructures by grazing incidence x-ray synchrotron radiation indicates that they have a perovskite PbTiO3 structure with a <100> preferred orientation and that are under strained conditions. Thermal treatments at higher temperatures produce the collapse of the ordered nanoparticles network and the formation of larger isolated particles of PbTiO3 with a truncated-pyramid morphology. Piezoresponse Force Microscopy studies demonstrate that these PbTiO3 nanostructures can be switched and that they have piezoelectric activity. These results support the potentiality of a fabrication strategy for the preparation of nanoferroelectrics onto substrates of interest in future nanoelectronic devices.

To learn more about this research see the full scientific highlight at:

2.  Science Highlight — The Structure of a Reaction Intermediate in Enzymatic Halogenation
       (contact: P. Riggs-Gelasco, College of Charleston)

Halogenated natural products play important roles as antibiotics, antifungals, and antitumor agents. The process of halogenation involves the replacement of a hydrogen with a halide (such as chloride or bromide), and is a challenging task for a synthetic chemist. However, the iron-containing enzymes in the haloperoxidase and halogenase families readily catalyze these reactions. It is thought that when this reaction occurs, the iron in the enzyme is at a high-valent Fe(IV) state, and that this species is responsible for removing a hydrogen atom (called an abstraction) from the substrate, creating a substrate radical, and that a halogen radical is subsequently transferred to the substrate to complete the halogenation reaction. Recently, Pamela Riggs-Gelasco and co-workers used x-ray absorption spectroscopy at SSRL's Beam Line 7-3 to obtain unique structural insights into this enzymatic intermediate in the halogenase CytC3. The extended x-ray absorption fine structure (EXAFS) data showed the presence of a short Fe-O bond and a Fe-Br interaction, clearly identifying a Br-Fe(IV)=O2- unit and confirming a key component in the enzymatic mechanism.

The reaction catalyzed by the halogenase CytC3.

To learn more about this research see the full scientific highlight at:

3.   Budget Impact on SSRL User Operations
       (contact: J. Stöhr,

As you know, since January there have been discussions about how the reduced budget will impact SSRL activities for this fiscal year. SSRL Lab Management has made the decision to continue the current user run as originally projected - ending at 6 am on Monday, August 11. However, there will be a 2-1/2 week shutdown June 30-July 15, 2008. During this period, we have scheduled Maintenance/Accelerator Physics (MA/AP) so that equipment related to top off injection can be installed. Other activities which would normally disrupt user operations may also be scheduled during this shutdown, such as seismic retrofit construction needed in Building 120.

Scheduling this shutdown in July will likely result in reduced power and labor costs, but more importantly, utilizing the down time to install and test top off equipment provides the opportunity of better understanding how the top off mode will impact beam line instrumentation, optics and user experiments before the next run begins in the fall. This will provide valuable information to proceed with the reviews and approvals needed for more frequent top off mode on all beam lines in the future. Results from these preliminary tests could then be shared with the user community at the next Users' Meeting in October.

Pending approval from DOE and SLAC Radiation Physics (RP), top off mode operation may be continued during the remainder of the run (July 16-August 11) on selected beam lines on the existing fill schedule of injection every 8 hours (but with shutters open on selected beam lines). RP may designate an 'exclusion area' around the selected beam lines and those areas may need to be cleared during the daily top off fills at 6 am, 2 pm, and 10 pm (fills usually take ~5 minutes). Little impact to user operations is anticipated as a result of these tests.
SPEAR Operating Schedule

4.   Very Small Spot Size Achieved at the New BL13-2
       (contact: H. Ogasawara,

Vertical spot size measurement at BL13-2 as a function of exit slit size. [larger version]
SSRL staff have been making progress on the soft x-ray emission spectroscopy capability at the new BL13-2 (first light at BL13 - the newest of SSRL's beam lines - and the description of its end stations - was reported in last month's SSRL Headlines). Soft x-ray emission spectroscopy is receiving growing attention for its unique ability to provide an atom-specific picture of the electronic structure in matter. Soft x-ray emission spectroscopy allows studies of many different samples: solids, surfaces, gases and liquids. The method is well suited to study gases and liquids and their solid interfaces since it is an x-ray-in/x-ray-out technique that does not require high vacuum. A typical soft x-ray emission spectrometer consists of an entrance slit, a spherical grating, and a 2D-detector. The entrance slit is the source point: a wide entrance slit gives high detection efficiency with low energy resolution, whereas a narrow entrance slit gives high energy resolution but low detection efficiency. SSRL staff is developing a high throughput x-ray emission spectrometer without an entrance slit and plan to use an extremely tightly focused beam at the sample on BL13-2. In this design, the detection efficiency will only depend on the acceptance angle of the grating and thereby the energy resolution will be determined by the size of the focal spot at the sample. To obtain typical resolving power (D E/E) of about 1000, the beam needs to be focused down to 10-20 microns along the dispersive direction (vertical). At the new BL13-2, a pair of Kirkpatick-Baez refocusing mirrors image the source horizontally and the exit slit vertically onto the sample. On March 22, SSRL staff achieved a key milestone during the current commissioning by measuring a beam size smaller than 5 microns in the vertical and 60 microns in the horizontal dimension at the sample. When fully commissioned, BL13 and its three stations will be opened as a general user beam line.

5.   SSRL School on Synchrotron X-ray Absorption Spectroscopy Techniques in Environmental and Materials Sciences: Theory and Application
       (organizers: S. Webb, J. Bargar, M. Toney and A. Mehta)

Modern synchrotron radiation based x-ray absorption spectroscopy (SR-XAS) techniques offer the ability to probe local molecular scale physical and electronic structures that govern key properties of technological and environmental materials and molecular complexes. The high collimation, intensity, and tunability of SR allow the investigation of a wide range of materials, including thin films and interfaces, nanoparticles, amorphous materials, solutions, hydrated and disordered minerals, soils, and dissolved species.

Good planning and a working knowledge of beam lines, in addition to techniques, are keys to conducting successful SR-XAS measurements. This third annual school on SR techniques will provide a practical users' guide to planning and conducting XAS/EXAFS measurements at SSRL beam lines. The school will cover important basics such as basic beam line setup and optimization for fluorescence and transmission spectroscopy, as well as advanced techniques including polarized single-crystal EXAFS, grazing incidence XAS, and microprobe XAS.

We will cover topics that are not commonly addressed in text books or class lectures, but are obtained only through on-the-experiment training. Tips on sample preparation, data collection, processing and analysis will be included. The first day of the school (May 20) will be a lecture day, followed by practical days with a full hands-on day at SSRL beam lines (May 21) and a third day of data analysis and discussion (May 22). Registration is limited, so please register early. Cost will be $75.

6.   Ultrafast X-ray Summer School, June 17-20, 2008
       (SLAC Today article by M. Cunningham)

The Linac Coherent Light Source (LCLS) will enable scientists to explore new chemical structures and processes. But before scientists grab the reins in this novel venture they'll have to go to school-Ultrafast X-ray Summer School, that is.

The Ultrafast X-ray Summer School, which is slated to run June 17-20, will hinge upon participant-oriented discussion and interaction focused on the state-of-the-art science that the LCLS will set in motion.

"There is a need to educate both senior scientists and younger scientists to generate a new class of researcher that will utilize this unique opportunity," Chairman Kelly Gaffney said. "And, for at least the next couple of years, this is the only place in the world it will be possible."

The LCLS has properties traditionally utilized in the laser community, but because it generates x-rays, it presents new opportunities. Techniques used in laser science and synchrotron x-ray science typically don't overlap-but the success of the LCLS will depend on the merging of these fields and the skill sets of each.

LCLS x-rays are expected to provide instantaneous images of atomic and molecular structures, which require a camera with sub-nanometer spatial resolution and a shutter speed of less than a trillionth of a second. This will generate unique opportunities for capturing single bimolecular structures and collecting real-time movies of chemical, physical and biological transformations.

Interested applicants can find registration and program information at the workshop website. Rooms at the Stanford Guest House are expected to fill quickly, so attendees are encouraged to make their reservations soon.

7.   2008 SSRL/LCLS Users' Meeting, October 15-18, 2008

Mark your calendar for the second joint SSRL and LCLS Users' Meeting and Workshops on October 15-18, 2008. Several parallel sessions for SSRL and LCLS science as well as joint sessions to discuss topics of general interest and to feature science highlights from the last year are being planned. SSRL specific workshops on October 15, will include: 1) Advanced Topics in EXAFS Analysis and Applications, 2) Macromolecular Crystallography, and 3) a joint ALS/SSRL workshop on Introduction to Synchrotron Radiation Experiments. LCLS workshops on October 17-18 will include: 1) Coherent X-ray Scattering and Imaging; 2) AMO/Strong Field Control of X-ray Processes, and 3) Soft X-ray Instrumentation for LCLS.

Contact the meeting organizers if you have suggestions for the annual meeting: Wayne Lukens (LBNL), Amyeric Robert (LCLS/SLAC), Riti Sarangi (SSRL/SLAC), and Linda Young (ANL). Start to think about topics which you may want to share through contributed talks or poster presentations; and consider nominating your colleagues for awards which will be presented at the annual Users' Meeting. The call for abstracts and award nominations will follow shortly. To review the 2007 meeting and workshop report, see

8.   Big Science Gets Small: New BL6-2 Microscope
       (SLAC Today article by B. Plummer)

New Microscope at BL6
Joy Andrews and Sean Brennan with the new nano-imaging x-ray microscope at BL6-2.
The size of big science at the Stanford Synchrotron Radiation Laboratory (SSRL) just got a little smaller, thanks to a new x-ray microscope installed last fall at Beam Line 6-2. As one of only a handful of such instruments in operation around the world, the new microscope offers SSRL researchers and users a new set of eyes for peering into the three-dimensional chemistry and structure of a range of materials from meteorites to mouse bones.

Spearheaded by Piero Pianetta and built by x-ray equipment supplier Xradia, the otherwise commercially available microscope takes advantage of the SPEAR3 synchrotron's incredible brightness to quickly capture three-dimensional images of structures as small as 40 nanometers, or about the size of the smallest virus.

"It's just like a typical microscope, but instead of looking with light, which has a relatively large wavelength, we're looking with x-rays, which have a very small wavelength," said Joy Andrews, SSRL staff scientist. "That way we can look at much smaller things."

In one recent study, Andrews and colleagues investigated the effects of weightlessness on the bones of mice to gather clues about the long-term effects of spaceflight on humans. Because of the high brightness of the SPEAR3 synchrotron beam, scans of bone tissue can be completed in a fraction of the time needed for similar studies using other x-ray sources.

The microscope works by passing a thin beam of x-rays through the sample, then through a special lens called a "zone plate" that enlarges the image onto a special screen. This special "phosphor" screen uses the same basic technology as a traditional television screen to convert the invisible x-ray image into a visible image which is then picked up by a specially designed digital camera.

The new microscope has the added advantage of using tunable x-rays that can be changed to reveal the chemistry of a sample, giving researchers the power to scrutinize materials to a level impossible without a synchrotron x-ray source.

To obtain a final, three-dimensional image, the sample is scanned dozens of times, rotating a fraction of a degree with each shot. The images are combined to construct a movie that reveals the nanoscale structural features of the sample.


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 Sciences. Additional information about SSRL and its operation and schedules is available from the SSRL WWW site.


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