As of June 4, 2011

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

Grazing-incidence inelastic X-ray scattering: lattice dynamics in thin films (May 19, 2011)

Inelastic X-ray scattering is a powerful modern tool to study lattice dynamics of condensed matter.  Recently an international team led by Dr. J. Serrano (Polytechnic University of Catalonia, Spain) has tried to extend the technique to several micron-thick systems by introducing grazing-incidence geometry.  Their sample is indium nitride grown on a sapphire substrate with a gallium nitride buffer layer inbetween, but X-rays only probe the surface, and not the substrate underneath.  The analysis was combined with ab initio calculations to determine the complete elastic stiffness tensor, the acoustic and low-energy optic phonon dispersion relations.  This finding could be a help in developing new types of solar cells.  For more information, see the paper, "InN Thin Film Lattice Dynamics by Grazing Incidence Inelastic X-Ray Scattering", J. Serrano et al., Phys. Rev. Lett. 106, 205501 (2011).

First-principle calculation of resonant X-ray emission spectra (May 16, 2011)

An interesting theoretical paper on the calculation of K edge resonant X-ray emission spectroscopy has been published recently.  The crystalline band structure was calculated using a quasiparticle self-consistent GW implementation, and then coherent spectra were obtained in the Kramers-Heisenberg formalism.  The calculated results for ZnO were compared with experiments.  For more information, see the paper, "First-principles calculation of resonant x-ray emission spectra applied to ZnO", A. R. H. Preston et al., Phys. Rev. B83, 205106 (2011).

Pump-probe X-ray microscopy: both time and spatial resolution (May 10, 2011)

A research team led by Professor J. Stohr (SLAC National Accelerator Laboratory, Stanford, USA) has recently performed time-resolved scanning transmission X-ray microscopy measurements to study the current-induced magnetization switching mechanism in nanopillars exhibiting strong perpendicular magnetic anisotropy.  Because of both the short-time (70 ps) and high-spatial (25 nm) resolutions of this imaging technique, the detailed mechanism has become clear as follows; after an incubation time of ~1.3 ns, a 100×300nm² ellipsoidal device switches in ~1 ns via a central domain nucleation and opposite propagation of two domain walls toward the edges.  For further understanding, micromagnetic simulations were done and shown as being in good agreement with experiments.  For more information, see the paper, "Nonuniform switching of the perpendicular magnetization in a spin-torque-driven magnetic nanopillar", D. P. Bernstein et al., Phys. Rev. B83, 180410(R) (2011).
 

X-ray spectra reveal color changes in historical paintings (May 9, 2011)

A research team led by Dr. L. Robinet (Synchrotron Soleil, Saint Aubin, France) has recently published an interesting paper describing how the blue pigment, smalt, has faded in many famous paintings such as "The Heavenly and Earthly Trinities (The Pedroso Murillo)" by Bartolome Esteban Perez Murillo.  The experiment was basically X-ray absorption spectroscopy near the Co K edge.  The samples were tiny pieces taken from the original paintings archived in the National Gallery, London and the Louvre Museum, Paris.  It was found that in intense blue particles the cobalt is predominantly present as Co²⁺ in tetrahedral coordination, while in colorless altered smalt the Co²⁺ coordination number in the glass structure is increased, and there is a transformation from tetrahedral towards octahedral coordination.  This change correlates with the alkali content as well, indicating that it is caused by leaching of potassium cations, which act as charge-compensators and stabilize the tetrahedral coordination of the cobalt ions that is responsible for the blue color.  For more information, see the paper, "Investigation of the discoloration of smalt pigment in historic paintings by Co K-edge micro X-ray absorption spectroscopy", L. Robinet et al., Anal. Chem., Article ASAP (DOI: 10.1021/ac200184f  Publication Date (Web) May 9, 2011).
 

Dedicated optical tweezers for synchrotron experiments (May 4, 2011)

Optical tweezers are widely used because they are capable of trapping small materials by highly-focused laser beams.  They are highly useful for manipulating single fragile objects.  Recently compact optical tweezers have been designed and developed specifically for synchrotron X-ray diffraction experiments.  Samples of a few micrometers up to a few tens of micrometers size can be trapped easily.  The selection and positioning of single objects out of a batch of many can be performed semi-automatically by software routines.  For more information, see the paper, "Optical Tweezers for Synchrotron Radiation Probing of Trapped Biological and Soft Matter Objects in Aqueous Environments", S. C. Santucci et al., Anal. Chem., Article ASAP (DOI: 10.1021/ac200515x  Publication Date (Web) May 4, 2011).
 

Near edge X-ray absorption imaging of geo-samples (April 18, 2011)

In most cases, rocks and geomaterials are chemically and structurally inhomogeneous.  The use of X-ray absorption spectro-microscopy is one promising solution, but the very long measuring time for scanning large samples with a tiny beam poses a limit for detailed analysis.  At the European Synchrotron Radiation Facility (ESRF) in Grenoble, France, scientists recently performed much more efficient and feasible experiments by coupling near-edge X-ray absorption spectroscopy and full-field transmission radiography with a large X-ray beam.  The method basically consists of the repeated acquisition of X-ray images as a function of X-ray energy near the absorption edge (in the present case, iron K edge).  The research group also combines this with polarization contrast imaging.  By looking at the Fe³⁺/Fe(total) image, some redox variations were found in the single mineralogical phase of complex metamorphic rocks.  The research group also analyzed bentonite analogue by separating the spectra into those of 5 simple minerals.  The material is a candidate for the storage of nuclear waste and CO₂, and the information is helpful in designing such applications.  For more information, see the paper, "Submicrometer Hyperspectral X-ray Imaging of Heterogeneous Rocks and Geomaterials: Applications at the Fe K-Edge", V. De Andrade et al., Anal. Chem., Article ASAP (DOI: 10.1021/ac200559r  Publication Date (Web) April 18, 2011).
 

Full-field phase contrast imaging with coded aperture and laboratory X-ray source (April 18, 2011)

Phase contrast X-ray imaging is a promising method for low Z samples which cannot always be properly imaged by conventional absorption and scattering imaging.  Recently Professor R. D. Speller (University College London) and his colleagues reported a novel way using a laboratory X-ray source outfitted with a pair of coded apertures; one in front of the sample for imaging and one behind it.  They were offset slightly to remove scattering background.  Readers might be aware that the method is quite similar to X-ray Talbot interferometry (for example, see the previous news article, "Micro-structure imaging using visibility contrast", No.5, Vol. 39 (2010)), when a 2D grating is used as a coded-aperture.  The technique could open up many interesting opportunities through its application to a wide range of fields, such as nano-bio technologies, because the experiments can be done with an ordinary incoherent X-ray source.  For more information, see the paper, "Noninterferometric phase-contrast images obtained with incoherent x-ray sources", A. Olivo et al., Appl. Optics, 50, 1765 (2011).
 

Use of zone plates to make X-ray microscopy more quantitative (April 8, 2011)

A group led by Professor C. Chang (University of Pennsylvania, USA) has recently reported a quantitative X-ray phase imaging method that can be readily implemented on existing facilities. This technique utilizes Fresnel zone plates both as imaging optical elements for magnification and as second-order grating structures for phase-shifting interferometry.  For more information, see the paper, "Quantitative x-ray differential-interference-contrast microscopy with independently adjustable bias and shear", T. Nakamura et al., Phys. Rev. A83, 043808 (2011).
 

Synchrotron micro X-ray diffraction of cement samples (April 4, 2011)

A German group led by Professor U. Panne (Humboldt University, Berlin) has recently reported the successful application of the micro X-ray diffraction technique to the evaluation of the durability of cements against reaction with sodium sulfate.  The experiments were done with a Debye-Scherrer camera equipped with a large-size CCD camera (3072×3072) and monochromatic micro beam (11.6 keV, 10 μm).  By moving the sample along the X-ray path, it is possible to obtain information at different depths, and the team could therefore eventually reconstruct the profile of each crystalline phase along the depth from the surface.  It was found that phase transformations proceeded during damage caused by penetration of sulfates.  For more information, see the paper, "Deciphering the Sulfate Attack of Cementitious Materials by High-Resolution Micro-X-ray Diffraction", M. C. Schlegel et al., Anal. Chem., 83, 3744 (2011).
 

Recovery commissioning at the Japanese synchrotron, The Photon Factory (May 31, 2011)

As reported in the previous news article, "Influence of the M9 class earthquake on synchrotron facilities in Japan", No.3, Vol. 40 (2011)), the Photon Factory, located to the north of Tsukuba city in Ibaraki prefecture, had to cancel all beamtime allocated in the term from May to September 2011.  However, scientists have devoted a great deal of time and effort to recovery work, and on May 16, the ring became capable of storing electron beams, and generating synchrotron radiation.  Recovery commissioning at each beamline started in the 4^th week of May.  Many users are involved in test experiments with their own samples.  Some readers may be interested in the status of BL-4A, which is the beamline for X-ray fluorescence spectroscopic analysis.  Recovery at the beamline appears more or less complete. Some data taken on March 10, one day before the earthquake, were reproduced almost perfectly.  Commissioning will continue until early July.  For further information, visit the Web page, http://www.kek.jp/ja/news/highlights/2011/PF_recovery.html (only in Japanese language).
 

Collaboration of DESY, XFEL and Brazilian LNLS (May 5, 2011)

The International Union of Crystallography (IUCr) has announced that Professor E. Dodson (Department of Chemistry, University of York, UK), Professor C. Giacovazzo (Institute of Crystallography-CNR, Bari, Italy) and Professor G.M. Sheldrick (Lehrstuhl fur Strukturchemie, Gottingen, Germany) have been awarded the ninth Ewald Prize for the enormous impact they have made on structural crystallography by designing new methods and providing these in algorithms and constantly maintained, renewed and extended user software. Their invaluable contributions to the computational side of the field have led to leadership with the program suites CCP4, SIR and SHELX, respectively.  The presentation of the prize will be made during the Madrid Congress Opening Ceremony in August 2011.  The Ewald Prize consists of a medal, a certificate and an award of USD 30,000.  Former recipients are D. Sayre (USA, 2008), P. Coppens (USA, 2005), M. M. Woolfson (UK, 2002), G. N. Ramachandran (India, 1999), M. G. Rossmann (USA, 1996), N. Kato (Japan, 1993), B. K. Vainshtein (Russia, 1990), J. M. Cowley (USA) and A. F. Moodie (Australia) in 1987.
 

9th Ewald Prize - E. Dodson, C. Giacovazzo and G.M. Sheldric (April 26, 2011)

In the presence of German President Christian Wulff and Brazilian President Dilma Rousseff, the three directors of DESY, the European XFEL, and LNLS have signed a cooperation agreement in Brasilia.  For further information, visit the Web page, http://www.xfel.eu/news/2011/brasilian_german_agreement/
 

Japanese X-ray free electron laser (March 29, 2011)

RIKEN and the Japan Synchrotron Radiation Research Institute (JASRI) have announced the start-up of the X-ray Free Electron Laser (XFEL) facility in Harima, named “SACLA” (SPring-8 Angstrom Compact Free Electron Laser).  For further information, visit the Web page, http://xfel.riken.jp/eng/index.html
 

PANalytical’s extension of XRD machine for SAXS application (April 26, 2011)

PANalytical has released new hardware and software for small-angle X-ray scattering (SAXS) measurements on their range of X-ray diffraction (XRD) systems.  For existing users, the SAXS capability is a straightforward addition to the instrument.  With the release of software, EasySAXS v2.0, nanoparticle analysis could become easier.  For further information, visit the web page, http://www.panalytical.com/
 

Canon sells Xradia’s 3D X-ray microscopy system (May 16, 2011)

Xradia, Inc., has announced a partnership agreement with Canon Marketing Japan, Inc., which will become the exclusive distributor of X-ray computer tomography system for industrial applications, research laboratories and synchrotron facilities throughout Japan.  For further information, visit the web page, http://www.xradia.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/