As of March 28, 2013

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

Application of ptychography to visualization of dislocations in silicon single crystal (March 7, 2013)

Professor Y. Takahashi (Osaka University, Japan) and his colleagues have recently reported that coherent X-ray imaging using Bragg diffraction can aid the observation of nanoscale dislocation strain fields in a silicon single crystal.  The experiments were done with 11.8 keV micro-focused X-ray photons, around 1 μm in both directions, using KB mirrors at BL-29XUL, SPring-8, Japan.  In this research, a 1 μm thick silicon (100) single crystal was placed in the X-ray path so that X-rays could pass through it and the 220 Bragg reflection spot was observed by a CCD camera 2 m behind the sample. The sample was scanned in XY directions as well.  The research team found phase singularities, i.e., two pairs of vortices with opposite directions in the phase map, that corresponded to the locally dark positions in the intensity map.  It was concluded that this corresponded to the projection of the {111} dislocation loops.  For more information, see the paper, "Bragg x-ray ptychography of a silicon crystal: Visualization of the dislocation strain field and the production of a vortex beam", Y. Takahashi et al., Phys. Rev. B87, 121201(R) (2013).

X-ray fluorescence holography with 50W low power X-ray source (February 28, 2013)

Dr. P. Korecki (Jagiellonian University, Poland) and his colleagues have recently published a fairly  impressive, successful 3D analysis of Cu₃Au (001) single crystal by white-beam X-ray fluorescence holograms measured using a 50W tungsten X-ray tube (50 kV, 1 mA, with 0.8mm Al filter).  Primary X-ray photons at the aperture, which is placed at 340 mm from the source, are around 2×10⁸ counts/sec.  The sample was positioned 610 mm from the sample, and was rotated relative to the incident beam around two axes (θ, φ).  The X-ray fluorescence intensity of Cu K and Au L lines was measured by a Si drift detector (SDD) with a 25 mm² effective area, placed at a distance of 12 mm from the sample. The typical counting rate was around 10⁵ counts/sec, and the total acquisition time was ~90 h, i.e., 4 days.  It was demonstrated that a 3D image of the sample was reconstructed from the recorded holograms.  Readers might be surprised to know that such a non-efficient experiment can be done even with a low power source.  As the authors claim at the end of this paper, the measuring time can be reasonably shortened by the use of more powerful laboratory X-ray sources.  For more information, see the paper, "Element sensitive holographic imaging of atomic structures using white x rays", K. M. Da.browski et al., Phys. Rev. B87, 064111 (2013).

3D chemical mapping with confocal X-ray fluorescence spectro-microscopy (February 27, 2013)

Dr. B. Kanngießer (Technische Universität Berlin, Germany) and her colleagues have recently reported further advances in 3D chemical mapping using a confocal X-ray fluorescence setup.  The research group has obtained nondestructive reconstruction of stratified systems with constant elemental composition but with varying chemical compounds.  For more information, see the paper, "Three-Dimensional Chemical Mapping with a Confocal XRF Setup", L. Luhl et al., Anal. Chem., Article ASAP (DOI: 10.1021/ac303749b).
 

Accuracy and uncertainties of V Kβ spectral profile (February 26, 2013)

A team led by Professor C. T. Chantler (University of Melbourne, Australia) has published vanadium Kβ spectra from metallic foil, measured with medium energy resolution but with high accuracy.  For more information, see the paper, "Characterization of the Kβ spectral profile for vanadium", L. F. Smale et al., Phys. Rev. A87, 022512 (2013).
 

"Measure and Sort" approach to reduce jitter in femtosecond pump-probe experiments (February 17, 2013)

In spite of the recent advent of few fs pulse X-ray free-electron laser sources, so far, synchronization between optical lasers and X-ray pulses has been challenging, and the jitter, typically, 100~200 fs r.m.s., has limited the time-resolution of the measurement.  At the Linac Coherent Light Source (LCLS), Stanford, scientists have recently solved this problem by introducing a "measure-and-sort" approach, which records all single-shot data with time information to ensure resorting of the data.  In the beamline, the same optical laser beam is split into three beams: with the first, the relative delay between laser and X-ray is encoded into wavelength by using a broadband chirped supercontinuum; in the second, the temporal delay is spatially encoded; in the third, pump-probe experiments are performed with time-sorting tools.  It was concluded that the error in the delay time between optical and X-ray pulses can be substantially improved to 6 fs r.m.s., leading to time-resolved measurement with only a few fs resolution.  For more information, see the paper, "Achieving few-femtosecond time-sorting at hard X-ray free-electron lasers", M. Harmand et al., Nature Photonics, doi:10.1038/nphoton.2013.11; published online, February 17, 2013.
 

Multiple ionization of krypton at around L edges by X-ray free-electron laser (February 19, 2013)

The extremely high peak power of an X-ray free electron laser pulse can be an attractive tool for clarifying the core-level excitation and relaxation process.  Recently, Dr. B. Rudek and his colleagues have reported their time-of-flight ion spectroscopy studies on sequential inner-shell multiple ionization of krypton at photon energies at 2 keV and 1.5 keV, which are higher than the LI (~1.92 keV) and lower than the LIII (~1.67 keV) edges for ordinary neutral krypton, respectively.  The experiments were done with two X-ray pulse widths (5 and 80 fs) and various pulse energies (from 0.07 to 2.6 mJ), at the Linac Coherent Light Source (LCLS), Stanford, USA.  The highest charge state observed at 1.5 keV photon energy (below the LI edge) is Kr¹⁷⁺; at 2 keV photon energy (above the LIII edge), it is Kr²¹⁺.  It was found that theoretical calculations based on a rate-equation model can explain the obtained experimental data for 1.5 keV, but fails to do so at 2 keV, where the experimental spectrum shows higher charge states. They discussed that this enhancement is due to a resonance-enhanced X-ray multiple ionization mechanism, i.e., resonant excitations followed by autoionization at charge states higher than Kr¹²⁺, where direct L-shell photoionization at 2 keV is energetically closed.  For more information, see the paper, "Resonance-enhanced multiple ionization of krypton at an x-ray free-electron laser", B. I. Cho et al., Phys. Rev. A87, 023413 (2013).
 

Energy shifts of Ti Kα induced by polarized ultrashort infrared laser pulse (February 13, 2013)

One promising application of laser-matter interactions is generating hot suprathermal electrons with keV-MeV energy, which enables excitation of the K shell of the target material.  Recently, Dr. G. Cristoforetti (Intense Laser Irradiation Laboratory, Italy) and his colleagues have reported some interesting experiments on the laser pulse polarization effect on the Kα yield and line shape.  The research group studied the interaction of an ultrashort laser pulse (λ = 800 nm, τ = 40 fs) with a Ti foil under intense irradiation.  The K X-ray emission was analyzed by a quartz crystal and a CCD camera, and it was found that the energy of Kα lines shift a few eV up to around 15 eV, depending on the pulse polarization.  Such dependence can be discussed by considering the efficiency of hot electron generation.  For more information, see the paper, "Spatially resolved analysis of Kα x-ray emission from plasmas induced by a femtosecond weakly relativistic laser pulse at various polarizations", G. Cristoforetti et al., Phy. Rev. E87, 023103 (2013).
 

Lens-less high-resolution imaging with partially coherent X-ray photons (February 7, 2013)

Coherent X-ray diffractive imaging has made remarkable progress over the past 15 years.  The technique basically reconstructs real space microscopic images with the spatial resolution of nm without the use of lenses, mainly because of the ability to retrieve phases.  However, it relies on the degree of high coherence of the available X-ray photon beam, and, until now, almost all experimental studies have been subject to some limits.  It is not very easy to satisfy the ideal conditions, mainly because of the partial coherence of the beam itself and some decoherence caused by imperfect detection as well as the dynamic motions of the sample.  Dr. P. Thibaut (Technische Universität München, Germany) and his colleague have recently reported their analytical studies into extending ptychography by formulating it as low-rank mixed states.  The procedure is closely related to quantum state tomography and is equally applicable to high-resolution microscopy, wave sensing and fluctuation measurements.  They concluded that some of the most stringent experimental conditions in ptychography can be relaxed, and susceptibility to imaging artifacts is reduced even when the coherence conditions are not ideal.  For more information, see the paper, "Reconstructing state mixtures from diffraction measurements", P. Thibault et al., Nature, 494, 68 (2013).

Final magnet girders installed at NSLS II, Brookhaven (March 6, 2013)

The construction of Brookhaven's National Synchrotron Light Source II is approaching its final stage. Recently the last of 150 magnet girders was installed in the storage ring.  Magnets traveled from across the globe, supplied by ring magnet vendors based in six countries: Buckley Systems Ltd (New Zealand), Budker Institute of Nuclear Physics (Russia), Danfysik (Denmark), Everson Tesla Incorporated (U.S.), Institute of High Energy Physics (China), and Tesla Engineering (U.K.).  In the experimental hall, meanwhile, 17 hutches have been delivered and constructed for seven beamlines; CSX1 and CSX2 (two branches of Coherent Soft X-ray Scattering and Polarization),     CHX (Coherent Hard X-ray Scattering), IXS (Inelastic X-ray Scattering), HXN (Hard X-ray Nanoprobe), SRX (Submicron Resolution X-ray Spectroscopy) and XPD (X-ray Powder Diffraction).  For further information, visit the Web page, http://www.bnl.gov/ps/news/news.php?a=23725
An explanation of the CSX beamline construction can be viewed on You Tube. http://www.youtube.com/watch?feature=player_embedded&v=rximpW0aR9A
 

Three US scientists awarded 2013 Japan Prize (January 30, 2013)

The Science and Technology Foundation of Japan has announced that three US scientists have been named as laureates of the 2013 (29th) Japan Prize.  Professors Grant Willson (University of Texas at Austin) and Jean Fre'chet (King Abdullah University of Science and Technology) have received the prize in this year’s category of "Materials and Production" for their development of chemically amplified resist polymer materials for innovative semiconductor manufacturing process.  Professor John Frederick Grassle (The State University of New Jersey) was selected in the other prize category of "Biological Production and Biological Environment" for his contributions to marine environmental conservation through research on ecology and biodiversity of deep-sea organisms. They will receive certificates of merit, and commemorative medals.  There is also a cash award of fifty million Japanese yen for each prize category.  The presentation ceremony is scheduled to be held in Tokyo on Wednesday 24^th, April, 2013.  The prize categories for the 2014 (30th) Japan Prize will be "Electronics, Information and Communications" and "Life Science".  For further information, visit the Web page, http://www.japanprize.jp/en/index.html. Selected scenes from the 2012 ceremony can be viewed on You Tube. http://www.youtube.com/watch?v=E6PhvtTdgt8&feature=youtu.be

PANalytical’s new XRF software (March 12, 2013)

PANalytical has launched new software for X-ray fluorescence (XRF) systems.  Stratos is a brand new software package, for both the Epsilon 3 and Axios spectrometer ranges. The company will also be releasing an upgrade of the FingerPrint software for the Epsilon 3 range.  For further information, visit the web page, http://www.panalytical.com/Home.htm
 

Rigaku introduces biological SAXS (February 15, 2013)

Rigaku Corporation has announced the introduction of the new BioSAXS-1000 AUTO, a leap forward for experimental biological SAXS (small angle X-ray scattering) workflow for the home lab.  For further information, visit the web page, http://www.rigaku.com/

Hitachi High-Tech Science relocates Tokyo sales office (March 15, 2013)

Hitachi High-Tech Science Corp. has announced that its sales department’s Tokyo office will move to a new address, 24-14, Nishi-Shimbashi 1-chome, Minato-ku, Tokyo 105-0003, Japan, and commence operation from April 1, 2013.  For further information, visit the web page, http://www.hitachi-hitec-science.com/en/
 

Bruker opens two new centers of excellence in Mumbai and Bengaluru (February 26, 2013)

Bruker has announced the grand openings of its new Mumbai and Bengaluru Centers of Excellence (CoE).  For over 30 years, the company has grown sales and service capabilities in most major cities in India, including New Delhi, Mumbai, Bengaluru, Chennai, Kolkata, Lucknow and Hyderabad.  For further information, visit the web page, http://www.bruker.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/