As of February 28, 2010

for international journal X-Ray Spectrometry (John Wiley & Sons Ltd.)

X-rays unveil the mystery of color changes in Van Gogh’s paintings (February 14, 2011)

Recently, a European international research group led by Professor K. Janssens (Antwerp University, Belgium) has succeeded in solving the scientific mechanism of color darkening in the paintings of Vincent van Gogh.  Some readers may remember a previous news article, "Synchrotron XRF revealed Van Gogh's hidden painting", No.5, Vol. 37 (2008), which explained how synchrotron X-ray spectroscopy and imaging are powerful tools in the analysis of such paintings.  In the present work, the research group discusses the change in color from yellow to dark brown in two Van Gogh paintings, Bank of the Seine (1887) and View of Arles with Irises (1888).  They also systematically studied the aging process of artificial samples using pigments.  The chrome yellow pigment is chemically lead chromate (PbCrO₄), which may include some amount of PbSO₄ and/or PbO.  During their research based on X-ray micro-spectroscopy, it was found that part of the material is transformed into hydrated chromium oxide (Cr₂O₃・2H₂O), which is known as viridian, i.e., a blue-green pigment under sunlight or UV light irradiation.  They also noted the formation of other Cr(III) compounds. Their conclusion was that the color change is due to the reduction from Cr(VI) to Cr(III) on the surface of the paintings, and the formation of a thin layer containing Cr(III).  This would be the reason for the brownish color.  Most of the experiments were done at beamline ID21 at the European Synchrotron Radiation Facility (ESRF, Grenoble, France).  For more information, see the papers, "Degradation Process of Lead Chromate in Paintings by Vincent van Gogh Studied by Means of Synchrotron X-ray Spectromicroscopy and Related Methods. 1. Artificially Aged Model Samples" and "2. Original Paint Layer Samples", L. Monico et al., Anal. Chem., 83 1214-1231 (2011).

High-resolution V Kα spectra of catalysts (February 8, 2011)

A Japanese research group led by Professors J. Kawai (Kyoto University) and T. Yamamoto (Tokushima University) has recently published a series of high-resolution X-ray fluorescence spectra for supported vanadium oxide catalysts.  The measurement was done with a double crystal spectrometer (Si 220 reflections with (+, +) arrangement), and the typical energy resolution was around 2.5 eV.  The authors were successful in discussing quantitatively the difference in chemical states among the catalysts supported on the different oxides, amorphous SiO₂, γ-Al₂O₃, and TiO₂ (anatase/rutile = 7/3).  For more information, see the paper, "Quantitative Chemical State Analysis of Supported Vanadium Oxide Catalysts by High Resolution Vanadium Kα Spectroscopy", T. Yamamoto et al., Anal. Chem., Article ASAP (DOI: 10.1021/ac102681z  Publication Date (Web): February 8, 2011).

Calculation of L X-ray production cross sections of heavy metals (February 4, 2011)

Dr. J. M. Fernandez-Varea (Universitat de Barcelona, Spain) and his colleagues have recently studied the emission of Lα, Lβ, and Lγ characteristic X-rays by the impact of electrons on Hf, Ta, W, Re, Os, Au, Pb, and Bi atoms.  They calculated the ionization cross sections of the LI, LII, and LIII subshells of these atoms within the distorted-wave Born approximation, and compared them with the published experimental data.  For more information, see the paper, "Lα, Lβ, and Lγ x-ray production cross sections of Hf, Ta, W, Re, Os, Au, Pb, and Bi by electron impact: Comparison of distorted-wave calculations with experiment", J. M. Fernandez-Varea et al., Phys. Rev. A83, 022702 (2011).
 

Femto-second coherent X-ray diffraction imaging of tiny proteins using X-ray free electron laser (February 3, 2011)

Two very exiting experimental reports have been published on the application of an X-ray free electron laser (XFEL) at Linac Coherent Light Source (LCLS, Stanford, USA).  An international research team led by Dr. H. Chapman (DESY, Hamburg, Germany) and Professor J. Hajdu (Uppsala University, Sweden) has demonstrated a new advanced stage of protein crystallography, which uses only tiny proteins instead of preparing large-size crystals.  This could open up new possibilities for the analysis of proteins that have been difficult or even impossible to prepare so far.  The technique has been basically known as coherent X-ray diffraction imaging.  The present research is the first experimental application of extremely brilliant femtosecond XFEL pulses.  In addition to the demonstration of snapshots of nano-crystalline proteins, they have reported the first single-shot images of intact viruses.  For more information, see the papers, "Femtosecond X-ray protein nanocrystallography", H. N. Chapman et al., Nature, 470, 73 (2011) and "Single mimivirus particles intercepted and imaged with an X-ray laser", M. M. Seibert et al., Nature, 470, 78 (2011).
 

Theoretical models for molecular imaging under significant damage by X-ray free electron laser (February 1, 2011)

One of hottest topics related to the application of an X-ray free electron laser (XFEL) is how to determine the structure of non-crystalline membrane proteins.  There has been a clear conflict between the incident brightness required to achieve diffraction-limited atomic resolution and the electronic and structural damage induced by such illumination.  Professors K. A. Nugent and H. M. Quiney (ARC Centre of Excellence for Coherent X-ray Science, University of Melbourne, Victoria, Australia) have recently published their theoretical research on this problem.  They have improved the imaging model by using optical coherence theory and quantum electrodynamics, and concluded that the analysis is far more tolerant of electronic damage than believed so far.  For more information, see the paper, "Biomolecular imaging and electronic damage using X-ray free-electron lasers", H. M. Quiney et al., Nature Physics, 7, 142 (2011).
 

Total-reflection inelastic X-ray scattering (January 18, 2011)

Many readers of this news column are familiar with total-reflection X-ray fluorescence (TXRF).  They also know that experiments can be done with a wavelength-dispersive mode, besides ordinary measurement with a silicon drift detector or a Si(Li) detector.  If the spectrometer is optimized to see inelastic X-ray scattering spectra, what happens?  Very recently, a research team led by Dr. P. H. Fuoss (Argonne National Laboratory, USA) published a very interesting report. The experiment used soft X-rays to observe the electronic structure of a 10-nm-thick La_0.6Sr_0.4CoO₃ epitaxial layer grown on a SrTiO₃ substrate.  By comparing data acquired under total X-ray reflection and penetrating conditions, it was found that the O K-edge spectra from a 10 nm thin film and that from the underlying substrate can be separated successfully.  For more information, see the papers, "Total-Reflection Inelastic X-Ray Scattering from a 10-nm Thick La0.6Sr0.4CoO3 Thin Film", T. T. Fister et al., Phys. Rev. Lett. 106, 037401 (2011).
 

Continuous Wavelet transform of XRF spectra (January 11, 2011)

Dr. S. Arzhantsev (Center for Drug Evaluation and Research, US Food and Drug Administration, St. Louis) and his colleagues have published some very interesting research.  The research group is engaged in the determination of toxic metals in pharmaceutical materials using hand-held XRF spectrometers.  It is extremely important with respect to toxic metal contamination to establish a reliable technique for classifying a large number of samples.  As the procedure is basically a kind of pattern recognition, the problem that needs to be overcome is finding a suitable filter for signals and noises in XRF spectra.  The research group chose a continuous Wavelet transform, which is an extension of short-time Fourier transform (STFT) and is capable of constructing a time-frequency representation of a signal that offers very good time and frequency localization.  In the paper, they discussed the comparison of the signal-to-noise ratios at the energies of the elements of interest obtained by wavelet filtering and those obtained by the conventional empirical method.  The results were evaluated in a collaborative study that involved 5 different hand-held XRF spectrometers used by multiple analysts in 6 separate laboratories across the United States, leading to more than 1200 measurements.  The detection limits estimated for arsenic, lead, mercury, and chromium were 8, 14, 20, and 150 μg/g, respectively.  For more information, see the paper, "Rapid Limit Tests for Metal Impurities in Pharmaceutical Materials by X-ray Fluorescence Spectroscopy Using Wavelet Transform Filtering", S. Arzhantsev et al., Anal. Chem., 83, 1061 (2011).
 

Synchrotron X-ray analysis of star dust brought back by Japanese satellite HAYABUSA (February 2, 2011)

Scientists in Japan have been using two synchrotrons, the SPring-8 and the Photon Factory, to analyze the dust particles collected by the HAYABUSA Asteroid probe, which returned from Asteroid Itokawa on June 13, 2010. HAYABUSA, which means "Falcon" in Japanese, was launched from the Uchinoura Space Center in Japan on May 9, 2003, and arrived at Itokawa in September 2005.  The HAYABUSA particles were initially analyzed using electron microscopes, and then forwarded to the above synchrotron facilities in January 2011.  Many interesting 3D images were collected at BL20XU, SPring-8, and the structure and chemical compositions were also analyzed at BL-3A, Photon Factory, KEK.  For more information on the HAYABUSA project, visit the web page of the Japan Aerospace Exploration Agency (JAXA, http://www.isas.jaxa.jp/e/enterp/missions/hayabusa/index.shtml
 

Two US and two Japanese scientists awarded 2011 Japan Prize (January 25, 2011)

The Science and Technology Foundation of Japan has announced that Japanese and US scientists have been named as laureates of the 2011 (27th) Japan Prize.  Dr. Dennis M. Ritchie, 69, Distinguished Member of Technical Staff Emeritus, Bell Labs, and Dr. Ken Thompson, 67, Distinguished Engineer, Google Inc., have received the prize in this year’s category of "Information and Communications" for developing the operating system (OS), UNIX, in 1969.  Dr. Tadamitsu Kishimoto, 71, Professor Emeritus, Osaka University and Dr. Toshio Hirano, 63, Dean of the Graduate School of Medicine, Osaka University, were selected in the other prize category of "Bioscience and medical science" for their discovery of interleukin 6 (IL-6), a cell-signaling molecule in the immune system and its application in treating diseases.  They will each receive a certificate of recognition and a commemorative gold medal at an award ceremony during Japan Prize Week in Tokyo on April 20, 2011.  A cash award of 50 million Japanese yen (approximately US$600,000) will also be given to each field - this year the two laureates in each field will split the prize equally.  The prize categories for the 2012 (28th) Japan Prize will be "Environment, Energy, Infrastructure" and "Healthcare, Medical Technology".  For further information, visit the web page, http://www.japanprize.jp/en/index.html
 

PANalytical’s new energy-dispersive XRF spectrometer (January 31, 2011)

PANalytical has announced its new range of Epsilon 3 benchtop spectrometers.  For further information, visit the web page, http://www.panalytical.com/
 

New Niton FXL for mining and exploration (January 31, 2011)

Thermo Fisher Scientific Inc. has announced the launch of the Niton FXL field X-ray lab as the newest member of its family of X-ray fluorescence analyzers.  For further information, visit the web page,  http://www.thermoscientific.com/niton

PANalytical acquires XRF laboratories from British Geological Survey (February 2, 2011)

PANalytical (Almelo, the Netherlands) has acquired the XRF laboratories from the British Geological Survey (BGS).  For further information, visit the web page, http://www.panalytical.com/

ON Semiconductor acquires CMOS image sensor business unit from Cypress (January 27, 2011)

ON Semiconductor (Nasdaq: ONNN) and Cypress Semiconductor Corp. (Nasdaq: CY) have announced that a definitive agreement has been signed for ON Semiconductor to acquire the CMOS Image Sensor Business Unit (ISBU) from Cypress in an all cash transaction for approximately $31.4 million. The transaction is expected to close by the end of the first quarter of 2011.  For further information, visit the web page, http://www.onsemi.com/
 

SpectroscopyNow.com

For additional news about X-ray analysis and other spectroscopy sciences, browse the Wiley website.

Kenji Sakurai
Director, X-Ray Physics Group, National Institute for
Materials Science (NIMS)
and Professor, Doctoral Program in Materials Science and
Engineering, Graduate School of Pure and Applied Sciences,
 University of Tsukuba
1-2-1, Sengen, Tsukuba, Ibaraki 305-0047 Japan
Phone : +81-29-859-2821, Fax : +81-29-859-2801
sakurai@yuhgiri.nims.go.jp
http://www.nims.go.jp/xray/lab/