As of July 31, 2010

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

Micro-structure imaging using visibility contrast (July 26, 2010)

Dr. W. Yashiro (University of Tokyo, Japan) and his colleagues recently reported an interesting application of X-ray Talbot interferometry, which usually gives absorption and differential-phase images.  As micro-structures of the sample distort X-ray wave fronts, the research group quantitatively discusses how visibility reduction is caused and influenced.  They also experimentally demonstrate that this new type of experimental method using visibility contrast is feasible for imaging micro-structures, which have been studied by ultra small angle X-ray scattering so far.  For more information, see the paper, "On the origin of visibility contrast in x-ray Talbot interferometry", W. Yashiro et al., Optics Express, 18, 16890 (2010).  For more information on visibility contrast, see the paper, "Hard x-ray dark-field imaging using a grating interferometer", F. Pfeiffer et al., Nature Materials, 7, 134 (2008).

Carbonates of iron-magnesium on the surface of Mars (July 23, 2010)

NASA’s Mars Exploration Rover Spirit has obtained some significant data on the detailed chemical composition of the rock exposed on the ground surface of the Columbia Hills of the Gusev crater.  It was found that the rock is a Mg-Fe carbonate (Mc_0.62Sd_0.25Cc_0.11Rh_0.02, where Mc = magnesite, Sd = siderite, Cc = calcite, and Rh = rhodochrosite) and a forsteritic olivine (Fo_0.72Fa_0.28, where Fo = forsterite and Fa = fayalite).  This could suggest extensive aqueous activity under near-neutral pH conditions that would be conducive to habitable environments on early Mars.  On this occasion, in addition to a X-ray spectrometer, a Mossbauer (MB) spectrometer and Miniature Thermal Emission Spectrometer (Mini-TES) greatly contributed to the findings.  For more information, see the paper, "Identification of Carbonate-Rich Outcrops on Mars by the Spirit Rover", R. V. Morris et al., Science 329, 421 (2010).

A novel technique for high-resolution soft X-ray lensless imaging (July 23, 2010)

The recent advent of coherent soft and hard X-ray sources has facilitated the development of imaging techniques that are capable of being inverted to the real space information extremely quickly.  A research group at the SLAC National Accelerator Laboratory, USA, recently developed a novel technique for soft X-rays, based on differential holographic encoding, termed holography with extended reference by autocorrelation linear differential operation (HERALDO).  The technique has achieved superior resolution over other similar lensless techniques, such as X-ray Fourier transform holography, while maintaining the signal-to-noise ratio and algorithmic simplicity.  The spatial resolution was 16 nm, and this was obtained by synthesizing images in the Fourier domain from a single diffraction pattern, which allows resolution improvement beyond the reference fabrication limit.  In addition to the capability of instant high-resolution reconstruction, the technique is found to be robust against data imperfections.  It reduces artifacts arising from the commonly-missing central low-q data.  For more information, see the paper, "High-Resolution X-Ray Lensless Imaging by Differential Holographic Encoding", D. Zhu et al., Phys. Rev. Lett. 105, 043901 (2010).  For more information on the original idea of HERALDO, see the paper, "Holography with extended reference by autocorrelation linear differential operation", M. Guizar-Sicairos and J. R. Fienup, Optics Express, 15, 17592 (2007).
 

X-ray reflectivity evidence of the existence of the gap between water and hydrophobic surface (July 16, 2010)

For many years, scientists have argued about the existence of a depletion gap between water and hydrophobic surfaces.  Several recent reports based on high-resolution synchrotron X-ray reflectivity seemed to give a positive conclusion, but they were not in good agreement quantitatively, mainly because the amount being discussed was at experimental resolution.  A research group led by Professor P. Dutta (Northwestern University, Illinois, USA) has recently reported some synchrotron X-ray reflectivity results on the interface between water and self-assembled monolayers.  To enlarge the depletion gap (if any) as much as possible, they chose hydrophobic fluoroalkylsilane, CF₃(CF₂)₅(CH₂)₂SiCl₃ and CF₃(CF₂)₁₁(CH₂)₂SiCl₃, of which the contact angles were 111 deg and 120 deg, respectively.  It was found that the depleted region width increased with contact angle and exceeded the resolution.  They also concluded that the contribution of its fluctuation to the interface roughness was substantially smaller than has been considered so far.  For more information, see the paper, "How Water Meets a Very Hydrophobic Surface", S. Chattopadhyay et al., Phys. Rev. Lett. 105, 037803 (2010).
 

X-ray fluorescence gives new insight into Leonardo Da Vinci's painting technique (July 14, 2010)

X-ray fluorescence has provided new information on the technique known as "sfumato", which Da Vinci and other Renaissance painters used to produce delicate gradations in tones or colors across the canvas.  Dr. P. Walter (Laboratoire du Centre de Recherche et de Restauration des Musees de France, CNRS, France) and his colleagues recently performed quantitative chemical analysis on seven paintings from the Louvre Museum (including the Mona Lisa), by synchrotron X-ray fluorescence at the European Synchrotron Radiation Facility (ESRF).  They were able to clarify how the painter made shadows on faces by the use of layers of glaze or a very thin paint, and by means of the nature of the pigments or additives.   For more information, see the paper, "Revealing the sfumato Technique of Leonardo da Vinci by X-Ray Fluorescence Spectroscopy", L. de Viguerie et al., Angewandte Chemie International Edition (Published Online: Jul 14 2010, DOI: 10.1002/anie.201001116).
 

A short period cryogenic undulator for future compact X-ray FEL (July 13, 2010)

Short period, high field undulators can enable short wavelength free electron lasers (FELs) at low beam energy.  A research group led by Professor J. Rosenzweig (University of California, Los Angeles, USA) has recently unveiled a new design based on an approach that utilizes cryogenic materials.  For more information, see the paper, "Short period, high field cryogenic undulator for extreme performance x-ray free electron lasers", F. H. O’Shea et al., Phys. Rev. ST Accel. Beams 13, 070702 (2010).
 

A novel soft X-ray diffractometer at Diamond Light Source (July 12, 2010)

Soft X-ray resonant diffraction and reflectivity have become one of the most promising tools with which to study magnetic materials. At Diamond Light Source, Oxfordshire, UK, a novel instrument for single crystal diffraction and thin film reflectivity experiments in the soft X-ray regime has been designed and constructed.  It is basically a limited three circle (q, 2q, and c) diffractometer with an additional removable rotation (f), and is equipped with a liquid helium cryostat, and post-scatter polarization analysis.  For more information, see the paper, "RASOR: An advanced instrument for soft x-ray reflectivity and diffraction", T. A. W. Beale et al., Rev. Sci. Instrum. 81, 073904 (2010).
 

How silicon X-ray optics can survive against FEL power (July 8, 2010)

A Brazilian research group recently discussed the thermal influence of soft X-ray free-electron-laser (FEL) pulses on silicon substrate.  Such analysis is important, because the peak power of a single FEL pulse is roughly four orders of magnitude higher than that in conventional synchrotron light facilities.  Their detailed time-evolution analysis indicates that in a worst case scenario, the second pulse could be adversely affected by dynamic thermal distortion induced by the preceding pulse. For more information, see the paper, "Thermoelastic analysis of a silicon surface under x-ray free-electron-laser irradiation", A. R. B. de Castro et al., Rev. Sci. Instrum. 81, 073102 (2010).
 

"Hollow" neon atom created by X-ray laser excitation (July 1, 2010)

What happens when an atom is excited by extremely strong X-ray photons such as an X-ray laser?  A Stanford research group recently published a very exciting report on the ionization of neon  (Z=10) by X-ray laser at the Linac Coherent Light Source (LCLS) housed at the SLAC National Accelerator Laboratory in California, USA.  The laser used in this experiment is extremely powerful (10¹⁸ W/cm², 10⁵ X-ray photons/Ų), and the research group scanned the X-ray photon energy from 800 eV to 2,000 eV, as well as the pulse width from 80 fs to 230 fs.  As the K absorption edge of neon is around 867 eV, below this energy, X-rays can strip some of the eight weakly bound electrons from the outer L shell of the neon atom.  Such a process of peeling electrons from atoms would come as no surprise for readers of X-ray spectrometry.  Above the absorption edge, K shell electrons are preferentially ejected, creating 1s vacancies that are refilled by electrons from the L shell.  Before the relaxation occurs, the remaining K shell electron is even more tightly bound to the neon nucleus than in the ground state.  Therefore, the K absorption edge for the system with a 1s vacancy is higher than usual.  When the research team raised the X-ray photon energy to 993 eV, both electrons from the inner K shell were knocked out, ionizing the atom from the inside out – in other words, coring the atom.  With this "hollow" neon then, a completely empty K shell has been created for the first time by X-ray photons, though similar phenomena may be possible by means of ultra-high temperature plasma, extremely high-energy collision processes etc.  For more information, see the paper, "Femtosecond electronic response of atoms to ultra-intense X-rays", L. Young et al., Nature 466, 56 (2010).  In the same issue, there is an interesting account by Justin Wark, "X-ray laser peels and cores atoms", Nature 466, 35 (2010).
 

Calculation of Oxyzine K XAFS spectra to discuss hydrogen bond (June 30, 2010)

The nature of the hydrogen-bond network in water and ice is one of the most interesting scientific mysteries, as it is still unsolved and always keenly debated.  Professor R. Car (Princeton University, New Jersey, USA) and his colleagues recently published their calculation of the X-ray absorption spectra of water and ice with a many-body approach for electron-hole excitations.  Their calculation reproduces some experimental features, including the effects of temperature change in the liquid.  The spectral difference between the solid and the liquid has been explained by considering short-range order effects, such as the breaking of hydrogen bonds and a non-bonded molecular fraction in the first coordination shell.  For more information, see the paper, "X-Ray Absorption Signatures of the Molecular Environment in Water and Ice", W. Chen et al., Phys. Rev. Lett. 105, 017802 (2010).  For more information on the experimental XAFS spectra of water and ice, see the paper, "The Structure of the First Coordination Shell in Liquid Water", Ph. Wernet et al., Science, 304, 995 (2004).
 

Successful combination of infrared and X-ray spectroscopic imaging in the analysis of minerals (June 22, 2010)

A research group led by Professor C-U. Ro (Inha University, Korea) has recently reported the combined use of two techniques, attenuated total reflectance FT-IR (ATR-FT-IR) imaging and a quantitative energy-dispersive electron probe X-ray microanalysis, low-Z particle EPMA, for the speciation of mineral particles.  For more information, see the paper, "Speciation of Individual Mineral Particles of Micrometer Size by the Combined Use of Attenuated Total Reflectance-Fourier Transform-Infrared Imaging and Quantitative Energy-Dispersive Electron Probe X-ray Microanalysis Techniques", H-J. Jung et al., Anal. Chem. 82, 6193 (2010).
 

10^th anniversary of series of workshops on buried interface science with X-rays and neutrons (July 27, 2010)

The 2010 workshop on buried interface science with X-rays and neutrons was held at Nagoya University, Japan, on July 25-27, 2010.  This was the latest in a series of 15 workshops held since 2001; Tsukuba (December 2001), Niigata (September 2002), Nagoya (July 2003), Tsukuba (July 2004), Saitama (March 2005), Yokohama (July 2006), Kusatsu (August 2006), Kanda-Tokyo (December 2006), Sendai (July 2007), Sapporo (September 2007), Kanda-Tokyo (December 2007), Tsukuba (March 2009), Akihabara-Tokyo (July 2009) and Hiratsuka (March 2010).  There are increasing demands for sophisticated metrology in order to observe multilayered materials with nano-structures (dots, wires, etc), which are finding applications in electronic, magnetic, optical and other devices.  Solid-liquid interfaces are another very important research subject.  X-ray and neutron analysis is known for its ability to observe in a non-destructive manner even buried function interfaces as well as the surface.  In addition to such inherent advantages, recent remarkable advances in micro analysis and quick time-resolved analysis in X-ray reflectometry are extremely important.  The present workshop gathered together those with different research backgrounds, i.e., from semiconductor electronics to chemical bio materials, and even theoretical groups were invited to give insights into unsolved problems on buried interfaces.  The workshop proceedings will be published in IOP conference series: Materials Science and Engineering, no later than the end of 2010.
 

2010 EXSA award on outstanding career in X-ray Spectrometry (June 24, 2010)

Professor Rene Van Grieken (University of Antwerp, the chief editor of X-Ray Spectrometry journal) received the European X-ray Spectrometry Association’s "Outstanding Career in X-Ray Spectrometry" award during the European X-Ray Spectrometry Conference in Figueira da Foz, Portugal, on June 24, 2010.
 

Rigaku’s EDXRF application note adapted for RoHS regulation (June 30, 2010)

Applied Rigaku Technologies, Inc. has published a new application report describing the elemental analysis of Cl and elements regulated by RoHS in plastics. Analysis is shown for polyethylene. Empirical calibration summary and detection limits are shown and instrument repeatability is demonstrated.  For further information, visit the web page, http://www.rigaku.com/index_en.html

 

Roenalytic appoints new XRF representative in North America (July 19, 2010)

Roenalytic GmbH has appointed Eastern Applied Research Inc as its exclusive service and support representative in North America.  For further information, visit the web page, http://www.easternapplied.com/
 

Olympus acquires Innov-X Systems (July 2, 2010)

Olympus NDT has announced that it has acquired Innov-X Systems Inc., a manufacturer of portable X-ray fluorescence (XRF) analytical instruments based in Woburn, Massachusetts, USA.  Innov-X Systems, Inc. will be operated as a business division of Olympus NDT, retaining its current management team and employee base.  For further information, visit the web page, http://www.olympus-ims.com/en/
 

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/