November 2007 Archives

For many years, the simultaneous mapping of phases and chemical compositions subjected to extreme conditions has been one of biggest challenges in materials science. Professor J. M. Howe (Virginia University, USA) and his colleagues have reported the successful study of partially molten Al-Si-Cu-Mg alloy particles, for automobile and aerospace applications, during in situ heating by energy-dispersive X-ray spectroscopy in a transmission electron microscope. They have discovered some significant results, for instance, Al and Si concentrations change in a complementary and symmetric manner about the solid-liquid interface as a function of temperature. They also obtained direct evidence for homogeneous nucleation of the Al-rich solid. For more information, see the paper, "In Situ Determination of the Nanoscale Chemistry and Behavior of Solid-Liquid Systems", S. K. Eswaramoorthy et al., Science, 318, 1437-1440 (2007).

The 1^st tutorial course on the analysis of thin films and multilayers by X-ray reflectivity was held in Tsukuba, Japan, on November 29-30. The first and second days were for beginners and experts, respectively, but most of the total of 63 participants attended both of them. The textbook distributed at the school will be published in 2008. The 2^nd course will take place in March 2008. Further information is available at http://www.nims.go.jp/xray/ref/ (in Japanese only).

At the TOMCAT beamline of the Swiss Light Source at the Paul Scherrer Institute, a phase-contrast X-ray tomographic microscope was recently applied to some very interesting research - the identification and classification of small fossil seeds (0.5~1.8 mm long) of the Early Cretaceous in Portugal and North America. The conclusion is that these seeds belong to Gnetales and to Bennettitales. The experiment used a very fast tomography method, the algorithm of which was introduced by Bronnikov, and refined by Gureyev. For more information, see the paper, "Phase-contrast X-ray microtomography links Cretaceous seeds with Gnetales and Bennettitales", E. M. Friis et al., Nature, 450, 549-552 (2007).

The Pittsburgh Conference has released the topics for the Conferee Networking Sessions (CNS) which will be offered at Pittcon 2008, March 2-7, 2008, in New Orleans at the Ernest N. Morial Convention Center. The sessions were first introduced at Pittcon 2007, and the number has been increased to 27 for Pittcon 2008. Some of the topics included in the 2008 program are "Management and Certification of Reference Standards", "Analysis of Explosives and Energetics: From Forensic/Trace to Production Support", "Green Chemistry/Green Chemists in the Office, Lab and Schools: What Can I Do to Make our World "Greener"", " Information Management and Data Handling in the Laboratory", " Chemical Imaging: Instrumental and Analysis" etc. For further information, visit http://www.pittcon.org/

Lensless Fourier transform holography (FTH) is known as an imaging method suitable for high resolution X-ray microscopy with coherent X-rays. In FTH, there had been a limit on the spatial resolution, mainly because of the contradiction between the requirement on the numerical aperture and the realistic resolving power of high spatial frequency fringes that appeared in the hologram. Multiplexing, i.e., the use of multiple object and reference signals, can be one promising solution, because it extends the effective field of view. Recently, a research group led by Professor J. Stöh, a director of Stanford Synchrotron Radiation Laboratory (SSRL), has developed the technique further so that the measurement can be done by a single shot. Using patterned masks to provide multiple X-ray sources, the team demonstrated the ability to record images simultaneously at different parts of the sample. 3D imaging of ultrafast processes could become a reality if the method is combined with so-called pump-probe experiments. For more information, see the paper, "Extended field of view soft x-ray Fourier transform holography: toward imaging ultrafast evolution in a single shot", W. F. Schlotter et al., Optics Letters, 32, 3110-3112 (2007).