January 2007 Archives

260 scientists from 22 countries gathered on January 24-25 at the DESY research center in Hamburg for the first European XFEL Users' Meeting, which brought together the future users of the European X-ray laser facility. The first users' meeting marks the beginning of a series of regular workshops and meetings between the scientists interested in the research opportunities at the XFEL and the planners of the facility. For more information, contact Petra Folkerts, Press officer XFEL project, FLASH, DESY, Phone: +49-40-8998-4977, Fax: +49-40-8998-2020, petra.folkerts@desy.de, http://www.xfel.net

At Brookhaven National Laboratory, United States, researchers have recently found a novel way to generate a very short controllable free electron laser (FEL) pulse, which usually depends on the length of the electron pulse. The main idea is the use of a Ti:Sapphire laser that combines a 150 femtosecond (FWHM) pulse of light with the much longer electron beam. This leads to a femtosecond FEL pulse that keeps growing in intensity and shortening in time duration, which is attributed to a phenomenon called superradiance (for details, see, R. H. Dicke, Phys. Rev. 93, 99 (1954)). The present research is the first to experimentally observe the effects of superradiance in a FEL setup. The output FEL pulse duration was measured to be as short as 81 femtoseconds, a roughly 50% reduction compared to the input seed laser. Understanding how to produce these intense, ultrafast pulses of light could help scientists around the world as they begin to construct the next generation of light source facilities. For more information, see the paper, "Experimental Characterization of Superradiance in a Single-Pass High-Gain Laser-Seeded Free-Electron Laser Amplifier ", T. Watanabe et al., Phys. Rev. Lett. 98, 034802 (2007).

Professor J. Rodenburg and his colleagues from the University of Sheffield, UK and the Paul Scherrer Institute, Switzerland recently developed a novel X-ray microscope, which is very different from conventional microscopes developed so far, because it does not employ any optics to focus the beams. The lensless technique collects diffraction patterns from several overlapping areas in space, which provides information about how the rays interfere with each other after they have been diffracted through the object. This interference can then be calculated backwards to what the rays' previous phase changes must have been, giving a complete picture of the structure. Since this innovative technique relies on a special type of computation (called ptychographical iterative engine (PIE), for details, see H. M. L. Faulkner and J. M. Rodenburg, Phys. Rev. Lett. 93, 023903 (2004)), rather than specific equipment, it could also be used to boost the power of optical and even electron microscopes. For more information, see the paper, "Hard-X-Ray Lensless Imaging of Extended Objects", J. M. Rodenburg et al., Phys. Rev. Lett. 98, 034801 (2007)

Platinum is the most efficient electrocatalyst for accelerating chemical reactions in fuel cells for electric vehicles. However, the reactions that take place during the stop-and-go driving of an electric car cause the platinum to dissolve, which reduces its efficiency as a catalyst. Recently, a Brookhaven National Lab group led by Dr. R. Adzic found that adding gold clusters to the platinum electrocatalyst is effective in stabilizing and prolonging the life of the electrocatalyst. The group tested the performance under the oxidizing conditions of the O₂ reduction reaction and potential cycling between 0.6 and 1.1 V in over 30,000 cycles, and obtained successful results. X-ray absorption spectra measured at the Pt LIII edge clearly showed that the Au clusters contribute to protecting the platinum from being oxidized. The next step of the research is to duplicate the results in real fuel cells. For more information, see the paper, "Stabilization of Platinum Oxygen-Reduction Electrocatalysts Using Gold Clusters", J. Zhang et al., Science, 315, 220 (2007).

The Science and Technology Foundation of Japan has announced that French, German and U.K. scientists have been named as laureates of the 2007 (23rd) Japan Prize. Prof. Albert Fert, 68, of France and Prof. Dr. Peter Grunberg, 67, of Germany, will receive the prize in this year's category of "Innovative Devices Inspired by Basic Research." They discovered the phenomenon of giant magneto-resistance (GMR) and contributed to the development of innovative spin-electronics devices. Dr. Peter Ashton, 72, of the U.K. has been selected in another prize category of "Science and Technology of Harmonious Co-Existence." They will receive certificates of merit, and commemorative medals. There is also a cash award of fifty million Japanese yen for each prize category. The prize categories for the 2008 (24th) Japan Prize will be "Information Communication Theory and Technology" and the"Medical Genomics and Genetics". For further details of the Japan Prize, contact The Science and Technology Foundation of Japan, Phone: +81-3-5545-0551, Fax +81-3-5545-0554, info@japanprize.jp, http://www.japanprize.jp/English.htm

Icosahedral quasicrystals (i-QCs) are long-range ordered solids that show non-crystallographic symmetries such as five-fold rotations. Their detailed atomic structures are still far from completely understood, because most stable i-QCs form as ternary alloys suffering from chemical disorder. Recently, a French-Japanese collaborative team led by Professor A. P. Tsai (Tohoku University, Japan) has succeeded for the first time in obtaining a detailed structure solution for i-YbCd_5.7. Similar to normal crystals, i-QCs exhibit beautiful diffraction patterns, but their lack of periodicity prevents conventional analysis. However, mathematically, i-QCs can be seen as the projection in 3D of a structure that is periodic in a virtual space of higher dimension. This resolves the situation because it allows conventional crystallography to be used in the higher-dimensional space. The obtained result represents an essential starting point for finding the atomic structure of more complex i-QCs. The team's X-ray experiments were done with synchrotron X-rays at D2AM beamline, ESRF in Grenoble, France. For more information about the analysis, see the paper, "Atomic structure of the binary icosahedral Yb-Cd quasicrystal", H. Takakura et al., Nature Materials, 6, 58-63 (2007).