March 2008 Archives

It is known that a helical undulator does not generate any higher-order harmonics on the central radiation axis. As such, off-axis radiation in higher-order harmonics has been considered useless, but so far this problem has not been discussed further. Professor S. Sasaki and his colleagues (Argonne National Lab, USA) have recently published an interesting paper about this problem. They found that all the harmonics except the fundamental from a variable polarizing undulator, such as an Advanced Planar Polarized Light Emitter (APPLE) device, are expressed by Laguerre-Gaussian modes carrying orbital angular momentum, when it is phased to deliver circularly polarized radiation. As the advent of polarized X-ray sources has dramatically expanded the understanding of magnetism, the availability of intense X-ray beams carrying orbital in addition to spin angular momentum could open the door to new condensed matter research via X-ray scattering and spectroscopy methods. For more information, see the paper, "Proposal for Generating Brilliant X-Ray Beams Carrying Orbital Angular Momentum", S. Sasaki et al., Phys. Rev. Lett., 100, 124801 (2008).

Daniel S. Chemla, a world-leading physicist at the Lawrence Berkeley National Laboratory, California, USA has died at the age of 67 at his home in Kensington. Dr. Chemla had been ill for four years after suffering a stroke. He had been director of the Materials Science Division, and also of the Advanced Light Source. He also held an appointment as a professor of physics at UC Berkeley. Dr. Chemla was French, born in 1940 in Tunisia, and was a graduate of France's prestigious Ecole Nationale Superieure des Telecommunications. He received his Ph.D. in non-linear optics from the University of Paris in 1972. Dr. Chemla came to the United States in 1981 to work at AT&T's famed Bell Laboratories. In 1991, he was recruited to Berkeley Lab by then director Charles Shank, to become the first director of a newly formed Materials Sciences Division. Dr. Chemla earned particular praise because of his great leadership and contribution in resolving the Advanced Light Source's budget crisis. His achievements with the lab's nanoscale work also led the Department of Energy to select the Berkeley Lab for the opening of the first of five Nanoscale Science Research Centers in the US. Dr. Chemla named it "The Molecular Foundry." Dr. Chemla's great talents were not limited to science. He was a master of Karate - he won the 5^th degree black belt in karate, the highest rank awarded in Shotokan Karate of America. He translated Master Gichin Funakoshi's "Karate-do Kyohan", the widely accepted karate master text (Kodansha International Ltd. ISBN 0-87011-190-6) into French. Dr. Chemla was elected a Member of the National Academy of Sciences and a Fellow of the American Physical Society. He received the R.W. Wood prize of the Optical Society of America, and the Quantum Electronics Award of the IEEE Laser and Electro-Optics Society, and a Humboldt Research Award. Dr. Chemla is survived by his wife Berit, two children, Yann, an assistant professor of physics at the University of Illinois, Urbana-Champaign, and Britt Chemla Jones, an Art History lecturer in Houston, Texas. His biography was released by Berkeley Lab.
http://www.lbl.gov/today/2008/Mar/21-Fri/chemla-jump.pdf
The San Francisco Chronicle (March 24, 2008) carries an obituary written by David Perlman.

Issue 6, vol. 23 (2008) of the Journal of Analytical Atomic Spectroscopy (JAAS) is devoted to the theme of synchrotron radiation. As guest editors, Professors A. von Bohlen and M. Tolan (Technische Universitat Dortmund, Germany) compiled 1 critical review and 7 regular papers. The title and the first authors are as follows: "Synchrotron radiation induced TXRF", C. Streli et al., 792, "Synchrotron radiation and cultural heritage: combined XANES/XRF study at Mn K-edge of blue, grey or black coloured palaeontological and archaeological bone material", I. Reiche et al., 799, "The barium giant dipole resonance in barite: a study of soft X-ray absorption edges using hard X-rays", C. Sternemann et al., 807, "Non-destructive, depth resolved investigation of corrosion layers of historical glass objects by 3D Micro X-ray fluorescence analysis", B. Kanngieser et al., 814, "Applications of synchrotron-based micro-imaging techniques to the chemical analysis of ancient paintings", M. Cotte et al., 820, "A combination of synchrotron and laboratory X-ray techniques for studying tissue-specific trace level metal distributions in Daphnia magna", B. De Samber et al., 829, "Sodium sulfate heptahydrate: a synchrotron energy-dispersive diffraction study of an elusive metastable hydrated salt", A. Hamilton et al., 840, "Reference-free X-ray spectrometry based on metrology using synchrotron radiation", B. Beckhoff, 845. In the editorial column, the editors point out some very interesting facts on the number of publications in the field of synchrotron radiation applications. They investigated the ISI Web of Science database and found that 1991 was a critical year. The relevant Figure shows a big jump in the number of publications, somewhat resembling an absorption edge. This jump no doubt correlates to the several year delayed big pulses, i.e., the advent of the 3^rd generation sources, ESRF (1994), APS (1996) and SPring-8 (1997).

Recent advances in highly brilliant synchrotron sources including soft X-ray free-electron lasers have ushered in many new methods of microscopy. Coherent diffractive imaging (CDI) is one of the most promising ways of determining the nanoscale structures of non-crystalline materials. However, to enable phase determination, the intensity distribution must be sampled at a spacing finer than its Nyquist frequency, which in turn requires the sample to be finite. In other words, there are some limitations in the sample size. Recently, an Australian group led by Professor K. A. Nugent (University of Melbourne) proposed a new method, 'keyhole' CDI, which can reconstruct objects of arbitrary size. In this case, a beam is focused and the object is placed downstream of the focal point so that it is illuminated by a diverging wave. The geometry looks similar to that of in-line holography, but the requirements placed on the source and detector are different. The group attempted imaging by visible light and X-rays, and, using the latter, part of an extended object was imaged with a detector-limited resolution of better than 20 nm. For more information on the present experiments, see the paper, "Keyhole coherent diffractive imaging", B. Abbey et al., Nature Physics, advanced online publication, DOI: 10.1038/nphys896

The Chemical Heritage Foundation (CHF) announced that Dr. Leroy Hood (Co-director of the Nano Systems Biology Cancer Center (NSBCC) and President of the Institute for Systems Biology in Seattle, Washington) received the seventh annual Pittcon Heritage Award. Jointly sponsored by the Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy (Pittcon) and CHF, this award recognizes outstanding individuals whose entrepreneurial careers have shaped the instrumentation community, inspired achievement, promoted public understanding of the modern instrumentation sciences, and highlighted the role of analytical chemistry in world economies. Dr. Hood pioneered the techniques that made the rapid pace of the Human Genome Project possible.

Beryllium has exceptional material properties, and because of this, it is an essential element used in the aerospace, computer, electronics, and nuclear industries. For X-rays, it has been widely used as a window material. Dr. B. Zawisza (Silesian University, Poland) has recently reported the determination of beryllium by X-rays. One would think that it is not easy to determine such an extremely light element by XRF. The novel simple idea is indirect determination of cobalt in the precipitates, [Co(NH₃)₆][Be₂(OH)₃(CO₃)₂(H₂O)₂]・3H₂O, fove rmed from hexamminecobalt(III) chloride and ammonium carbonate-EDTA solution. The detection limit of the proposed method is 0.2 mg of beryllium. For more information, see the paper, "Determination of Beryllium by Using X-ray Fluorescence Spectrometry", B. Zawisza, Anal. Chem., 80, 1696 (2008).