October 2011 Archives

The recipient of the 6th Asada Award, which is presented by the Discussion Group of X-ray Analysis, Japan, in memory of the late Professor Ei-ichi Asada (1924-2005) to promising young scientists in X-ray analysis fields in Japan, is Dr. Takashi Yamamoto (Tokushima Univ., "Studies on pre-edge peak in XANES spectra of transition metals for empirical chemical state analysis"). The ceremony was held during the 47th Annual Conference on X-Ray Chemical Analysis, Japan, at Kyushu University, Fukuoka.

Professor J. Kawai (Kyoto University, Japan; Associate editor of X-ray Spectrometry) and his colleagues recently developed a novel tiny X-ray instrument equipped with a pyroelectric LiTaO₃ crystal as an electron source, a sample stage and an X-ray detector. The research group found that adequate X-ray fluorescence spectra can be measured for 0.03 mm² titanium, iron, and nickel wires. For more information, see the paper, "Development of Miniaturized Electron Probe X-ray Microanalyzer", S. Imashuku et al., Anal. Chem., 83, 8363 (2011).

One of the hottest topics in X-ray structural analysis is coherent X-ray diffraction measurement to obtain real-space images of nanoscale crystals. The key here is the method of phase retrieval. Until now, iterative projective algorithms have been frequently employed to recover the phase information from the amplitude measured in reciprocal space. The analysis relies on experimental data to be oversampled, and there have been difficulties in the case of highly strained structures, where information is below the Nyquist frequency. A research team led by Professor I. K. Robinson (University College London, UK) has recently reported a new method, called a density modification phase reconstruction algorithm, to solve this problem. This is a successful extension of the recent compressive sensing theory and works well in solving the nonconvex phase retrieval problem for highly strained crystalline materials. For more information, see the paper, "Phase retrieval of diffraction from highly strained crystals", M. C. Newton et al., Phys. Rev. B 82, 165436 (2010).

Empirical and semiempirical K-shell fluorescence yields (ωK) and Kβ/Kα intensity ratios for ZnCo alloy with various chemical compositions, leading to differences in pH, have recently been published. The samples were excited by 59.5-keV γ rays from a ²⁴¹Am annular radioactive source, and X ray fluorescence spectra were measured by an Ultra-LEGe detector. For more information, see the paper, "Effect of pH treatment on K-shell x-ray intensity ratios and K-shell x-ray-production cross sections in ZnCo alloys", N. Kup Aylikci et al., Phys. Rev. A84, 042509 (2011).

European XFEL and the Spanish Center for Ultrashort Ultraintense Pulsed Lasers (CLPU) in Salamanca will pool their efforts to promote research into high-energy density science and to develop new ultrafast lasers to analyze physical and chemical processes in conjunction with the X-ray beams of the European XFEL. Both research institutions signed a memorandum of understanding at the European XFEL headquarters in Hamburg. In the framework of this cooperation, an optical laser expert from CLPU has now joined the European XFEL Optical Lasers Group for an initial period of six months. For further information, visit the web page, http://www.xfel.eu/

A German group led by Dr. B. Beckhoff (Physikalisch-Technische Bundesanstalt (PTB), Berlin) recently analyzed quantitatively the buried B₄C nanolayer on a silicon substrate by using synchrotron radiation at BESSY II. The thickness and elemental composition were successfully determined by reference-free X-ray fluorescence spectrometry under conventional and grazing-incidence conditions. For more information, see the paper, "Complementary Characterization of Buried Nanolayers by Quantitative X-ray Fluorescence Spectrometry under Conventional and Grazing Incidence Conditions", R. Unterumsberger et al., Anal. Chem., 83, 8623 (2011).