May 2007 Archives

A research group at the Japan Atomic Energy Agency (Kizugawa, Japan) has recently developed a novel table-top pulsed X-ray source. The source employs a Ti:sapphire laser, emitting 70 fs duration 2 TW pulses of 800 nm wavelength at 10 Hz. The laser beam is focused to the flow of high-density Ar gas. The source was applied to perform phase contrast imaging. For more information, see the paper, "Phase-contrast x-ray imaging with intense Ar Ka radiation from femtosecond-laser-driven gas target", L. M. Chen et al., Appl. Phys. Lett. 90, 211501 (2007).

The Advanced Photon Source (APS) and APS Users Organization has announced that the 2007 Arthur H. Compton Award has been presented jointly to Andrzej Joachimiak and Gerold Rosenbaum of Argonne National Laboratory for pioneering advances and leadership that helped to establish the APS as a premier location worldwide for protein crystallography research. Former recipients of the award are: Gunter Schmahl and Janos Kirz (2005), Martin Blume, Doon Gibbs, Kazumichi Namikawa, Denis McWhan (2003); Wayne A. Hendrickson (2001); Sunil K. Sinha (2000); Donald H. Bilderback, Andreas K. Freund, Gordon S. Knapp, Dennis M. Mills (1998); Philip M. Platzman, Peter M. Eisenberger (1997); Nikolai Vinokurov, Klaus Halbach (1995). For more information, contact Eleanor Taylor, Phone, +1-630-252-5565, etaylor@anl.gov

Theodore H. Maiman, the American physicist who made the first working laser, died on March 5, 2007 at the age of 79 from systemic mastocytosis in Vancouver, Canada, where he lived with his wife. Maiman's laser, based on a synthetic ruby crystal grown by Dr. Ralph L. Hutcheson, was first operated on 16 May 1960 at Hughes Research Laboratories in Malibu, California. It is well-known that this breakthrough was based on the idea of employing artificial rubies as the active medium for the laser at a time when others were trying only various gases. Dr. Maiman would have been aware of errors in their calculations. Another key point is that he also used pulses of light to excite atoms in the ruby. This was the ground-breaking first step to the modern pulse laser. Although his paper on this wonderful discovery was unfortunately mistakenly rejected by Physical Review Letters, the shortened version was published in Nature ("Stimulated Optical Radiation in Ruby", T. H. Maiman, Nature, 187, 493 (1960)). Dr. Maiman received the Japan Prize in 1987. He is the author of a book entitled "The Laser Odyssey" (Laser Press, 2000). The New York Times (May 11, 2007) carries an obituary written by Douglas Martin.

Recently, some very interesting research on magnetic noise from antiferromagnets has been published. Unlike ferromagnets, the characteristics of which have been studied for many years, antiferromagnets have remained a mystery because their internal structure was too fine to be measured. Their internal order is on the same scale as the wavelength of X-rays, and therefore, X-ray photon correlation spectroscopy, which measures 'speckle' patterns, can give a unique 'fingerprint' of a particular magnetic domain configuration. It was found that the domain wall motion is thermally activated at temperatures above 100 K, but not so at lower temperatures. For more information, see the paper, "Direct measurement of antiferromagnetic domain fluctuations", O. G. Shpyrko, et al., Nature 447, 68 (2007).

For many years, the existence of magnetic carbon has remained an enigma. Previous claims to have solved the mystery were subsequently disproved when it was found that magnetic metals like iron, nickel, etc, were probably present in the carbon samples. Recently, Dr. Ohldag (Stanford Synchrotron Radiation Laboratory) and his colleagues have shown that pure carbon can be made permanently magnetic at room temperature after carrying out a series of careful measurements including scanning transmission X-ray microscopy, X-ray magnetic circular dichroism (XMCD), PIXE analysis (to check for contamination by magnetic metals), AFM, and MFM etc. The team found that the magnetic order originates only from the carbon p-electron system. For more information, see the paper, p-Electron Ferromagnetism in Metal-Free Carbon Probed by Soft X-Ray Dichroism", H. Ohldag et al., Phys. Rev. Lett., 98,187204 (2007).

The Center for Functional Nanomaterials (CFN) has opened at Brookhaven National Laboratory, United States. The CFN is dedicated to the fabrication and study of nanoscale materials, with an emphasis on atomic-level tailoring to achieve desired properties and functions. The science at the CFN is organized around three scientific themes; (i) nanocatalysis, (ii) biological and soft nanomaterials, and (iii) electronic nanomaterials. The official opening ceremony will be held on May 21. For more information, visit http://www.bnl.gov/cfn/