As of November 30, 2010

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

Recent progress of U-shaped rotating anode X-ray source (November 5, 2010)

A U-shaped design for rotating anode X-ray sources is one method for enabling high brilliance, and was first proposed by Professor N. Sakabe (KEK, Tsukuba, Japan) in 1995.  Unlike ordinary rotating anode X-ray sources, the electron beam goes beyond the outside surface of the rotating anode and then reverses its direction so that it can hit the inside surface.  In this case, because of the centrifugal force of the rotating anode, the surface can be much smoother than usual even near the melting point, enabling the production of more X-ray photons.  A KEK research group has published a report on recent progress with this type of X-ray source.  According to their simulation, by optimizing both the bending and the steering magnets, the beam size can be 0.45 mm (horizontal) × 0.05 mm (vertical) for a 120 keV/75 mA beam.  The effective brilliance is about 500 kW/mm².  For more information, see the paper, "Research and development of an electron beam focusing system for a high-brightness X-ray generator", T. Sakai et al., J. Synchrotron Rad. 18, (2011) (Published online, DOI:10.1107/S0909049510029948).

Calculation of L_{II, III} X-ray absorption spectra for 3d transition metals (November 3, 2010)

Professor P. Blaha (Technische Universität Wien, Austria) and his colleagues have recently calculated the X-ray absorption spectra at the L_{II, III} edges of the early 3d elements by solving the Bethe-Salpeter equation (BSE).  Under the independent particle approximation (IPA), X-ray absorption spectra are usually considered as proportional to the unoccupied part of the projected density of states weighted by the momentum matrix elements between the core and the conduction states.  However, due to the localization of the core wave function, the interaction of the exited electron with its hole is not negligible.  In particular, the branching ratio between the L_II and L_III edges cannot be explained.  Though the IPA gives 1:2, the observed ratios are much closer to 1:1 or even higher for K, Ca, Sc, Ti, and V.  They detailed this problem based on their BSE calculation.  For more information, see the paper, "Understanding the L2,3 x-ray absorption spectra of early 3d transition elements", R. Laskowski et al., Phys. Rev. B 82, 205104 (2010).

Calculation of X-ray emission from doubly ionized neon (October 25, 2010)

When an X-ray source with extremely high brilliance such as an X-ray free electron laser is used for X-ray spectroscopy experiments, we have to consider the significant population of the two core-hole states because of two-photon x-ray absorption (see, for example, the previous news article, ""Hollow" neon atom created by X-ray laser excitation" in X-ray Spectrometry, Vol. 39, No.5 (2010)).  A research group led by Professor F. Gel’mukhanov (Royal Institute of Technology, Sweden) has recently published the calculation of the resonant X-ray emission from a neon atom induced by the two-photon population of a double-core-hole excited state.  They studied mainly 2 cases; an off-resonant intermediate single-core-hole state, and a resonant core-ionized intermediate state.  For more information, see the paper, "Two-photon-induced x-ray emission in neon atoms", Y-P. Sun et al., Phys. Rev. A 82, 043430 (2010).
 

A laser-plasma base synchrotron radiation source (October 24, 2010)

A number of new methods have been proposed of late to produce X-ray photons with high brightness and short pulse duration, namely extremely high order harmonics from a laser, inverse Compton scattering and laser plasma acceleration.  Dr. S. Kneip and his colleagues have recently applied the last of these types of technology to a table top synchrotron X-ray source.  The method uses the phenomenon whereby the passage of an intense laser pulse through an underdense plasma generates a so-called plasma wakefield, which can have intrinsic fields of 1,000 times or more the best achievable by conventional accelerator technology.  Some readers might recall previous news articles, "Table-top soft X-ray undulator source" in X-ray Spectrometry, Vol. 39, No.1 (2010) and "A compact synchrotron light source driven by pulse laser", in X-ray Spectrometry, Vol. 37, No.2 (2008).  Both are pioneering reports on wakefield-driven synchrotron radiation.  After generating high-energy electrons by laser pulse, they tried to transport the beam to an undulator, which is a magnet array and usually known as an insertion device placed at the straight section of the storage ring.  In contrast, the electron beam in the plasma accelerator undergoes transverse (betatron) oscillations when subject to the focusing fields of the plasma wave, and the radiation wavelength can extend to the hard X-ray region as well.  The research group succeeded in enhancing the brilliance of this betatron radiation by optimizing the wakefield conditions.  They were able to accelerate electrons upto 230 MeV with a 5 mm path, and the critical energy of the obtained radiation was 6-10 keV.  For more information, see the paper, "Bright spatially coherent synchrotron X-rays from a table-top source", S. Kneip et al., Nature Physics, (2010) (Published online, DOI:10.1038/nphys1789).
 

Phase retrieval in highly strained crystals (October 20, 2010)

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).
 

Kβ/Kα intensity ratio in Ti_xCo_1-x alloy (October 17, 2010)

Dr. I. Han (Ağrι İbrahim Çeçen University, Turkey) and his colleagues have published a paper on the relationship between the Kβ/Kα X-ray fluorescence intensity ratio and valence-electron configurations in Ti_xCo_1-x (x = 0.7, 0.6, 0.5, 0.4, and 0.3).  For more information, see the paper, "Relative K x-ray intensity studies on valence-electron structure of Ti and Co in Ti_xCo_1-x alloys", I. Han et al., Phys. Rev. A82, 042514 (2010).
 

Separation of diffuse scattering in specular X-ray reflectivity measurement (October 8, 2010)

A research group led by Professor H. Zabel (Ruhr-Universität Bochum, Germany) has recently published an interesting paper discussing the solution to a well-known problem in X-ray reflectivity.  The technique is for layered thin films, and can give the layer thickness, surface/interface roughness and correlations of the interface roughness parallel and perpendicular to the interface.  Due to the finite size of the receiving detector slit, it will always collect not only pure specular reflection but also diffusely scattered radiation.  For many years, the separation of the diffuse contribution to the intensity of specular reflection has been an important topic for reliable data analysis.  The researchers propose several measurements using different slit openings for specular scans, and show some applications to realistic systems, such as periodic V/Fe multilayers prepared on MgO substrate, with V and Pd capping layers.  For more information, see the paper, "Separation of the diffuse contribution to the specular x-ray scattering of multilayer films", V. P. Romanov et al., Phys. Rev. B 82, 165416 (2010).
 

Aerosol analysis by soft X-ray spectromicroscopy near carbon absorption edge (September 30, 2010)

A research group at Lawrence Berkeley National Laboratory, USA, has recently published an interesting report on an automated data analysis method for submicrometer atmospheric particles containing organic and inorganic material.  The main idea is the use of X-ray spectral features in the energy range from 278 to 320 eV, which is near the carbon K-edge and potassium LII and LIII edges.  The method provides quantitative mapping of the spatial distribution of elemental carbon, organic carbon, potassium, and noncarbonaceous elements in particles of mixed composition.  It was recently applied to analyze differences in over 1000 particles collected at various times and locations in Mexico City to examine the effects of atmospheric aging on internally mixed atmospheric aerosol particles.  For more information, see the paper, "Automated Chemical Analysis of Internally Mixed Aerosol Particles Using X-ray Spectromicroscopy at the Carbon K-Edge", R. C. Moffet et al., Anal. Chem. 82, 7906 (2010).

JPCM’s special section on surfaces and buried interfaces research by X-rays and neutron techniques (December 1, 2010)

In Issue 47, vol. 22 (2010) of Journal of Physics: Condensed Matter, a special section features a compilation of articles on exploring surfaces and buried interfaces of functional materials by advanced X-ray and neutron techniques.  Many of the authors are members of a group established in the Japan Applied Physics Society, and this is their 9^th collection of articles since 2001.  Unlike many other surface-sensitive methods, these techniques do not require ultra high vacuum, and therefore, a variety of real and complicated surfaces fall within the scope of analysis.  It must be particularly emphasized that the techniques are capable of seeing even buried function interfaces as well as the surface.  Furthermore, the information, which ranges from the atomic to mesoscopic scale, is highly quantitative and reproducible.  Such features are fairly attractive when exploring multilayered materials with nanostructures (dots, tubes, wires, etc), which are finding applications in electronic, magnetic, optical and other devices.  Visit the Web page to download the papers in this collection, http://iopscience.iop.org/0953-8984/22/47
 

National Geographic’s news column on 115-year-old X-ray photo (November 8, 2010)

W. Rontgen took the world’s first X-ray photo on November 8, 1895, thereby creating the very famous X-ray image of his wife’s fingers.  Ker Than has written a short article in National Geographic News on this X-ray photo.  For more information, see the article, " 115-Year-Old X-Ray", http://news.nationalgeographic.com/news/2010/11/photogalleries/101108-x-rays-google-doodle-115th-anniversary-years-science-pictures/?now=2010-11-08-00:01

The 5th Asada award (October 22, 2010)

The recipient of the 5th 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. Tsutomu Kurisaki (Fukuoka Univ., "Development of a novel soft X-ray absorption spectroscopic measurement apparatus and structural analysis of various metals ions and metal complexes in aqueous solution").  The ceremony was held during the 46th Annual Conference on X-Ray Chemical Analysis, Japan, at the Hiroshima Prefectural Information Plaza, Hiroshima.
 

PerkinElmer’s new X-ray flat panel detectors (November 15, 2010)

PerkinElmer has announced two new products in its Flat Panel Detector family, the XRD 0822 and XRD 1622, with effective area sizes of 20cm² and 41 cm², respectively.  The detectors are designed mainly for non destructive testing, and support an energy range above 20 keV.  The latitude range and the frame rate are ca. 13 bit and 100 Hz, respectively.  For further information, visit the web page, http://www.perkinelmer.com/
 

Rigaku’s application notes for the analysis of petrol (October 17, 2010)

Rigaku Corp has published three application reports for the petroleum market.  Two explain the elemental analysis of P, S, Ca, Zn, Mg, Ba, Cu and Cl in a typical lubricating oil formulation using respective empirical and fundamental parameters (FP) calibration methods.  The third details the measurement of sulfur in ULSD (ultra-low sulfur diesel) by ASTM D7220.  In the reports, calibration summaries and typical detection limits are presented, and instrument repeatability is demonstrated.  For further information, visit the web page, http://www.rigaku.com/
 

PANalytical’s new office in Houston, USA (October 11, 2010)

PANalytical Inc. has announced the opening of a new office with demonstration laboratory and meeting space near Houston, TX, USA.  For further information, visit the web page, http://www.panalytical.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/