As of September 30, 2010

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

3D nano-scale imaging without lenses: ptychographic X-ray computed tomography (September 23, 2010)

A research group led by Professor F. Pfeiffer (Technische Universitat Munchen, Germany) has recently reported an extremely powerful combination of X-ray tomography and ptychographic coherent imaging, which enables quantitative phase-contrast X-ray microscopy without any lenses.  A refractive index in the X-ray region is usually expressed as n = 1 - d - iβ, where d and β are real and imaginary parts, and relate to the phase shift and the attenuation, respectively.  The researchers developed a new method to give a 3D image of d rather than β, because d can give much higher visibility in samples based on low-Z elements, which are most likely in bio-medical applications. So far, phase-contrast X-ray imaging has had limitations in giving such quantitative information.  The use of coherent X-ray diffraction is one of the most promising solutions, and ptychography is a further extension that enhances precision in recovering the phase by introducing scanning of the sample.  As the spatial resolution of the computed images is no longer limited by the quality or resolving power of a lens, just a pinhole was used in the present research.  By combining such image reconstruction to obtain nano-scale 2D images with other image processing based on a back-filtered projection algorithm, they have succeeded in obtaining 3D images on the 100 nm scale of bone structures such as the osteocyte lacunae and the interconnective canalicular network.  The experiments were done at X12SA beamline, Swiss Light Source.  For more information, see the paper, "Ptychographic X-ray computed tomography at the nanoscale", M. Dierolf et al., Nature, 467, 436 (2010).  In the same issue, there is an instructive account, "A new phase for X-ray imaging", H. N. Chapman, Nature, 467, 409 (2010).  For the details of ptychography, see the paper, "The Theory of Super-Resolution Electron Microscopy Via Wigner-Distribution Deconvolution", J. M. Rodenburg and R. H. T. Bates, Phil. Trans. Roy. Soc. (London) A339, 521 (1992).

X-ray photon correlation spectroscopy of azopolymer (September 23, 2010)

Professor M. P. Fontana (University of Parma, Italy) and his colleagues have recently reported X-ray photon correlation spectroscopy (XPCS) studies on poly[[4-pentiloxy-3'-methyl-4'-(6-acryloxyexyloxy)]azobenzene], which is a kind of photosensitive azo-polymer and is softened by photoisomerization.  XPCS uses coherent X-rays to measure small angle scattering, called a speckle pattern, which is caused by some inhomogeneities.  It gives information on the slow dynamics of various equilibrium and non-equilibrium processes in condensed matter systems.  The main advantage of using X-rays instead of other direct methods such as scanning probe microscopy is that it provides statistical information averaged over the whole sample as a function of the momentum transfer. This is essential for the analysis of dynamical heterogeneity and of nonequilibrium and aging effects in the observed dynamics.  The research group measured the time correlation functions at different temperatures and momentum transfers (q) and under different illumination conditions (dark, UV or blue light).  It was found that the correlation functions are well described by the so-called stretched exponential function with relaxation times that are proportional to the inverse of q.  They were able to determine the scaling laws for equilibrium and nonequilibrium fluctuations on local space scales.  For more information, see the paper, "Slow dynamics in an azopolymer molecular layer studied by x-ray photon correlation spectroscopy", D. Orsi et al., Phys. Rev. E82, 031804 (2010).

Theory of X-ray cross correlation and local symmetry (September 20, 2010)

Some readers might remember the news article, "A new technique with coherent X-rays to determine non-crystalline structures", in X-ray Spectrometry, Vol. 38, No.5 (2009).  The technique called X-ray cross correlation analysis (XCCA) is an extension of X-ray photon correlation spectroscopy, and is promising with respect to solving the atomic-scale structures of complicated disordered systems, which have for many years presented difficulties in terms of reaching a clear understanding of the structures.  Recently, Dr. M. Altarelli (European X-ray Free-Electron Laser Facility, Hamburg, Germany) and his colleagues published a paper on the theoretical treatment of XCCA.  They gave a general theory for the cross correlation function, and tried to interpret the experimental XCCA results for colloidal glass.  The authors plan further publications to present the results of various simulations as well.  For more information, see the paper, "X-ray cross-correlation analysis and local symmetries of disordered systems: General theory", M. Altarelli et al., Phys. Rev. B82, 104207 (2010).
 

Synchrotron X-ray diffraction hints at presence of magma ocean deep underground (September 17, 2010)

A geoscientists group at the European Synchrotron Radiation Facility (ESRF, Grenoble, France), has recently found that a natural fertile peridotite, which is a characteristic material of the Earth’s mantle, can be partially molten at a pressure of 140 GPa, when the temperature reaches 4,200 K.  This could reinforce the hypothesis of the presence of a deep magma ocean.  The experiments showed that the liquid produced during this partial fusion is dense and that it can hold multiple chemical elements, among which are important markers of the dynamics of the mantle.  For more information, see the paper, "Melting of Peridotite to 140 Gigapascals", G. Fiquet et al., Science, 329, 1516 (2010).
 

A dimensional standard for micro X-ray computer tomography (September 16, 2010)

Dr. B. M. Patterson (Los Alamos National Laboratory, USA) and his colleagues have recently published an interesting paper on analytical problems arising from micro X-ray computer tomography.  They discussed the use of a dimensional standard based upon NIST certified glass microspheres dispersed in a low density poly(styrene) matrix.  For more information, see the paper, "Dimensional Standard for Micro X-ray Computed Tomography", B. M. Patterson et al., Anal. Chem., Article ASAP (DOI: 10.1021/ac101522q  Publication Date (Web): September 16, 2010).
 

Kα satellite spectra in electron beam excitation (September 16, 2010)

Argentinian scientists have recently published a paper on the emission of X-ray satellite lines in the Kα region of Mg, Si, Sc, Ti, Cr, Fe, Ni, and Zn induced by an electron beam.  They studied Kα', Kα₃, Kα₄, Kα₅, Kα₆, and two transitions denoted here as Kα₂₂ and Kα₁₂.  The work is a continuation of their previous work (see, the previous article, "Kβ satellites in EPMA", in X-ray Spectrometry, Vol. 39, No.2 (2010).)  For more information, see the paper, "Kα satellite transitions in elements with 12 ≤Z≤30 produced by electron incidence", S. P. Limandri et al., Phys. Rev., A82, 032505 (2010).
 

TXRF analysis of selenium in soils (August 18, 2010)

Determination of the selenium content of soils is an important issue from the viewpoint of environmental and earth sciences. The work presents a lot of technical difficulties due to low concentrations within complex matrices.  Dr. E. Margui (Institute of Earth Sciences “Jaume Almera”, CSIC, Spain) and her colleagues have recently explored the possibilities of several analytical approaches combined with total reflection X-ray (TXRF) spectrometry.  While direct analysis of a solid suspension has a relatively poor detection limit of around 1 mg/kg, a dispersive liquid-liquid microextraction procedure (DLLME) before the TXRF analysis of the soil digest provides much greater detection power.  The detection limit is 0.05 mg/kg, which is comparable to or lower than previously published results.  For more information, see the paper, "Analytical Possibilities of Total Reflection X-ray Spectrometry (TXRF) for Trace Selenium Determination in Soils", E. Margui et al., Anal. Chem., 82, 7744 (2010).
 

A hard X-ray pulse source driven by short pulse laser (August 16, 2010)

Electrons accelerated by the interaction between an ultrashort laser pulse and a plasma and then injected into a cold target can create X-ray photons via bremsstrahlung as well as inner shell ionization.  The burst of K X-ray fluorescence from a metallic target is typically up to 10¹² photons/pulse with a duration of 100∼600 fs.  Dr. F. Zamponi (Friedrich-Schiller-University Jena, Germany) and his colleagues have recently published an interesting report.  Thin titanium foils were irradiated by ultraintense laser pulses at intensities up to ≈5×10¹⁹ W/cm², and X-rays emitted from the front and rear sides were measured using a high-resolution imaging system, which allows spectral analysis.  During the experiments, they found significant differences in intensity, dimension, and spectrum between front and rear side X-ray emission in the 3~12 keV range.  They explained such differences in terms of directional bremsstrahlung emission from fast electrons generated during the interaction process.  For more information, see the paper, "Directional Bremsstrahlung from a Ti Laser-Produced X-Ray Source at Relativistic Intensities in the 3-12 keV Range", F. Zampon et al., Phys. Rev. Lett., 105, 085001 (2010).
 

Pico-second time-resolved X-ray fluorescence analysis used to study spin-crossover system (August 9, 2010)

X-ray fluorescence spectra can give information on various chemical states, including spin states such as high-spin and low-spin.  Recently, Dr. G. Venko (KFKI Research Institute for Particle and Nuclear Physics, Hungary) and his colleagues published their research on light-induced spin crossover transition.  They studied the spin state of aqueous [Fe(bpy)3]²⁺ (bpy=2,2’-bipyridine) molecules, 60 ps after an ultrashort laser pulse excitation by time-resolved X-ray fluorescence.  The laser induces a low-spin to high-spin conversion, and then the system goes back to the low-spin state on a 0.1 ns timescale.  For more information, see the paper, "Picosecond Time-Resolved X-Ray Emission Spectroscopy: Ultrafast Spin-State Determination in an Iron Complex", G. Vanko et al., Angew. Chem. Int. Ed. 49, 5910 (2010).
 

Large area Fourier-Transform holography using a separated holographic mask (July 16, 2010)

Scientists led by Dr. N. Awaji (Fujitsu Laboratories, Japan) have recently reported successful large area imaging by Fourier transform holography in both soft and hard X-ray regions.  The key was the separation of a holographic mask from the sample, enabling the sample to then be scanned to increase the observation area (~10μm or even more), though the beam size was fairly limited (~1μm) to maintain good coherence.  They demonstrated some magnetic domain images of perpendicular magnetized film with soft X-rays (778 eV), and also some patterned samples and the cross-section of the Cu-interconnect-line with hard X-rays (5,500 eV).  The spatial resolution for the above energies was 42 and 75 nm, respectively.  The experiments were performed at SPring-8 (Harima, Japan).  For more information, see the paper, "Large Area Imaging by Fourier Transform Holography Using Soft and Hard X-rays", N. Awaji et al., Appl. Phys. Express 3, 085201 (2010).
 

CHESS receives $109 million in grants (September 30, 2010)

The Cornell High Energy Synchrotron Source (CHESS), at Cornell University (USA) has been granted a total of $109 million.  The National Science Foundation (NSF) has received $77 million to continue its existing operation of the facility through 2014 and $32 million for research and development of prototypes for the Energy Recovery Linac (ERL).  For further information, visit the web page, http://www.news.cornell.edu/stories/Sept10/ERLCHESS.html
 

Denver X-ray conference awards (August 4, 2010)

Conference: The 2010 Birks Award was presented to Victor Buhrke, Consultant, Portola Valley, CA to honor his significant contributions to the field of X-ray spectrometry.  The 2010 Hanawalt Award was given to Takeshi Egami, University of Tennessee, Knoxville, TN and Simon Billinge, Columbia University, New York, NY.  This award is presented every three years for an important, recent contribution to the field of powder diffraction.
 

JEOL’s ClairScope^TM (JASM-6200), an atmospheric SEM receives 2 prizes (September 30, 2010)

ClairScope (JASM-6200), an atmospheric scanning electron microscope developed jointly by JEOL Ltd. and Japan's National Institute of Advanced Industrial Science and Technology, has won the MT-10 Award for Microscopy Innovation from Microscopy Today, a journal of the Microscopy Society of America, and the R&D 100 Awards sponsored by R&D Magazine.  The MT-10 Award is given to the best new products and technologies in the field of microscopy.  Winners are selected from a wide range of fields including optical microscopy, scanning probe microscopy, electron microscopy, ion microscopy, acoustic microscopy, micro analysis, and sample preparation, etc. The award ceremony was held at the Microscopy & Microanalysis 2010 meeting in Portland Oregon.  The R&D 100 Awards identifies and celebrates the top high technology products of the year. Sophisticated testing equipment, innovative new materials, chemistry breakthroughs, biomedical products, consumer items, high-energy physics: the R&D 100 Awards spans industry, academia, and government-sponsored research.  For further information, visit the web page, http://www.jeol.com/
 

Bruker acquires Veeco (August 16, 2010)

Bruker Corporation (NASDAQ: BRKR) has announced the signing of an agreement to acquire the Scanning Probe Microscopy (SPM) and Optical Industrial Metrology (OIM) instruments business from Veeco Instruments, Inc. (NASDAQ: VECO) for $229 million in cash.  For further information, visit the web page, http://www.bruker-axs.de/news.html
 

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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/