A team led by Dr. M. Minitti (SLAC National Accelerator Laboratory, USA) has recently succeeded in recording the time evolution of a structural change of ring-type 1,3-cyclohexadiene gas molecule to linear 1,3,5-hexatriene. The employment of the X-ray free-electron laser at LCLS (Linac coherent light source), Stanford allowed them to do ultra fast snapshots of X-ray scattering in several tens of fs (femtosecond) scale. The study is based on pump-and-probe measurement; i.e., X-ray data were collected as a function of the controlled delay time between the UV pump pulse (267 nm, 65 fs, 4-8 μJ, 100 μm size) and X-ray probe pulse (8.3 keV, around 30 fs, 1012 photons/pulse, 30 μm square size). The team established that some signals caused by structural change are found as early as 30 fs, and the reaction finishes at 200 fs. For more information, see the paper, "Imaging Molecular Motion: Femtosecond X-Ray Scattering of an Electrocyclic Chemical Reaction", M. P. Minitti et al., Phys. Rev. Lett. 114, 255501 (2015).
Ms. Laura Bush, who is an editorial director of Spectroscopy, has recently published an article on the present and future of X-ray fluorescence on the occasion of Spectroscopy's celebration of 30 years. It is a summary of her interviews with experts. For more information, see the article, "Analysis of the State of the Art: XRF", Laura Bush, Spectroscopy, 30 (6) 86-94 (2015), which can be found online at http://www.spectroscopyonline.com/analysis-state-art-xrf A PDF file can also be downloaded from iTunes.
Coherent X-ray diffraction imaging is one of a number of recently developed lens-less microscopic techniques giving 2D real space structure when combined with phase retrieval data processing. A team in Shandong University in China has recently published an interesting observation of intact unstained magnetotactic bacteria. It was confirmed that the reconstructed images give some intercellular structures, such as nucleoid, polyβ-hydroxybutyrate granules, and magnetosomes, which have been identified by electron microscopy. The team was also successful in quantification of the density, i.e., it was found that the average density of magnetotactic bacteria is 1.19 g/cm3 from their data. The experiment was done with 5 keV X-ray photons at BL29XU, SPring-8, Japan. For more information, see the paper, "Quantitative Imaging of Single Unstained Magnetotactic Bacteria by Coherent X.ray Diffraction Microscopy", Jiadong Fan et al., Anal. Chem. 87, 5849 (2015).
A research group led by Professor Jorg Evers (Max Planck Institute for Nuclear Physics, Heidelberg, Germany) has recently reported a method for narrowing the spectral width of X-ray pulses by the use of subluminal light propagation. So far, in visible light, slow group velocity such as 17 m/sec has been observed in low temperature sodium gas at 435 nK (see, L. V. Hau et al., Nature, 397, 594 (1999)). The authors intend a similar effect in X-ray wavelength photons by manipulating the optical response of the 14.4 keV Mössbauer resonance of 57Fe nuclei. The method combines coherent control, as well as cooperative and cavity enhancements of light-matter interaction in a single setup. It was found that the reduced group velocity of the obtained X-ray pulses is lower than 10-4 of the speed of the light. For more information, see the paper, "Tunable Subluminal Propagation of Narrow-band X-Ray Pulses", K. P. Heeg et al., Phys. Rev. Lett. 114, 203601 (2015).
Professors D. A. Keen (Rutherford Appleton Laboratory) and A. L. Goodwin (University of Oxford) have recently published an interesting review paper on disordered structures. For many years, crystallographers have determined the structures of many complicated crystals with atomic or even sub-atomic resolution. On the other hand, the structures of disordered systems, which lack the crystalline periodic order, are still not well understood because of the limits of the analytical technique. Correlated disorder is a disorder, but maintains crystallographic signatures, which can be used for classifying the type of disorder. For more information, see the paper, "The crystallography of correlated disorder", D. A. Keen and A. L. Goodwin, Nature, 521, 303 (2015).
A Slovenian group has recently reported the Kα and Kβ emission spectra of phosphorus, measured by monochromatic synchrotron X-rays (3 keV, at ID26, ESRF) and a 2 MeV proton beam. They also compared them with a Density Functional Theory calculation using StoBe-deMon code (Stockholm-Berlin version of demon). For more information, see the paper, "Chemical State Analysis of Phosphorus Performed by X.ray Emission Spectroscopy", M. Petric et al., Anal. Chem. 87, 5632 (2015).
Readers may remember that electrochemical X-ray fluorescence developed by Prof. Julie V. Macpherson's group at Warwick University, England can analyze sub-ppb level heavy elements in solution (See, News in No.5, Vol.43 (2014)). Recently the research team published their successful extension of the technique to in situ time-evolution analysis. Their electrode is a freestanding film of boron-doped diamond, and it can work also as an X-ray window. Primary X-rays pass through the back side of the electrode and excite the heavy elements in the electrodeposit on the electrode. In addition to quantitative analysis of a mixed solution of Hg2+, Pb2+, Cu2+, Ni2+, Zn2+, and Fe3+(all at 10 μM concentration), time-evolution analysis of electrodeposition can be a very promising application of this unique method. For more information, see the paper, "Direct Identification and Analysis of Heavy Metals in Solution (Hg, Cu, Pb, Zn, Ni) by Use of in Situ Electrochemical X.ray Fluorescence", G. D. O'Neil et al., Anal. Chem. 87, 4933 (2015).
Scientists at Los Alamos National Laboratory have recently reported the X-ray analysis of uranium oxideα-U3O8 samples under controlled temperatures and humidities. They found that the combined use of powder X-ray diffraction and U L-III EXAFS can help in identifying temporal changes of uranium oxide stored for a number of years. For more information, see the paper, "Oxidation and Hydration of U3O8 Materials Following Controlled Exposure to Temperature and Humidity", A. L. Tamasi et al., Anal. Chem. 87, 4210 (2015).
A very interesting idea that proposes the use of a motor in a hard disk drive as an X-ray chopper has been recently published. It can produce X-ray pulses of ms width and few μs rise time. In the research, the system was used to test the response of X-ray detectors such as ionization chambers and photo diodes. For more information, see the paper, "Hard disk drive based microsecond x-ray chopper for characterization of ionization chambers and photodiodes", O. Muller et al., Rev. Sci. Instrum. 86, 035105 (2015).
National Synchrotron Light Source II of Brookhaven National Laboratory will officially start user runs from the 3rd cycle in 2015. Seven beamlines will be commissioned in September, 2015, and a further 21 beamlines will be designed and constructed in the coming years. The facility provides the world's smallest electron beam emittance, resulting in the brightest X-ray source. For more information, visit the Web page, http://www0.bnl.gov/ps/nsls2/about-NSLS-II.php
The following YouTube video also gives useful information.https://www.youtube.com/watch?v=AzP8EGHw4BA
A team led by Dr. T. Jach (NIST, USA) and Dr. W. T. Elam (University of Washington, USA) has recently published an interesting theoretical paper discussing the broadening of N K absorption and emission spectra of NH4NO3 and NH4Cl. The authors studied many-body lifetime effects in valence-band X-ray emission. For more information, see the paper, "Origins of extreme broadening mechanisms in near-edge x-ray spectra of nitrogen compounds", J. Vinson et al., Phys. Rev. B90, 205207 (2014).
The recipient of the 9th 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. Susumu Imashuku (Kyoto Univ.), "Portable electron probe microanalyzer using pyroelectric crystal". The ceremony was held during the 50th Annual Conference on X-Ray Chemical Analysis, at Tohoku University, Sendai.
So far, monochromatic X-rays have been used for 3D micro X-ray fluorescence analysis based on confocal geometry. Dr. P. Wrobel (AGH University of Science and Technology, Poland) and his colleagues have recently discussed the feasibility of polychromatic excitation. The research group described the full theoretical expression of matrix effects and geometrical effects for polychromatic X-ray photons in confocal arrangement. It was demonstrated that the introduction of effective energy approximation works well. For more information, see the paper, "Depth Profiling of Element Concentrations in Stratified Materials by Confocal Microbeam X-ray Fluorescence Spectrometry with Polychromatic Excitation", P. Wrobel et al., Anal. Chem., 86, 11275 (2014).
Professor L. Vincze (Ghent University, Belgium) and his colleagues have reported on the latest fluorescence mode XANES imaging using the SLcam, which is an energy dispersive pnCCD detector. At BM26A, ESRF, the measurements were done for iron foil with some oxides and geological standard samples. The typical detection limit and measuring time were 0.5 wt% and 15 h, respectively. Readers might think that energy-resolution can be sacrificed near the absorption edges of interest in order to shorten the measuring time in the same way as ordinary XANES measurement by means of X-ray fluorescence. Although the use of ordinary X-ray CCD in accumulation mode for a very similar experiment was published 10 years ago (for example, M. Mizusawa et al, J. Synchrotron Rad. 11, 209 (2004)), the present system has the advantage of being able to reduce the background from the major light elements contained in the sample. For more information, see the paper, "Full-Field Fluorescence Mode Micro-XANES Imaging Using a Unique Energy Dispersive CCD Detector", P. Tack et al, Anal. Chem., 86, 8791(2014).
Most X-ray experiments can be done at high quality with ease in an ordinary laboratory. Some experiments, however, have to be done in the field. It is hard to imagine a more extreme definition of "in the field" than the planet of Mars, which is why exciting times have come about since NASA's Mars rover "Curiosity" landed on Mars in August 2012. It has since recorded and sent back a large number of datasets including X-ray fluorescence (XRF) and X-ray diffraction (XRD) data. Naturally, the scientists involved with the projects have been speaking globally since. During EXRS 2014 (June, Bologna, Italy), Professor J. L. Campbell (University of Guelph, Canada) gave a keynote lecture entitled "XRF and PIXE on the Mars Science LAB Curiosity Rover". At the Denver X-ray conference (July, Big Sky, Montana), the Plenary Session was "X-rays on Mars", and 3 scientists gave lectures. Professor D. L. Bish (Indiana University) gave a talk entitled "The First X-ray Diffraction Results From Mars". Professor J. L. Campbell's talk on "XRF Combines with PIXE in Curiosity's Alpha Particle X-ray Spectrometer" was the extension on his talk at EXRS 2014, and further detailed and specific discussion was done there. Professor S.M. Clegg talked about "Exploring Mars with ChemCam on the Curiosity Rover" (ChemCam enables quick element determination by the laser-induced plasma emission spectroscopy). In August, at Montreal, during the International Union of Crystallography's congress, Professor D. L. Bish gave a talk entitled "The First X-ray Powder Diffraction Measurements on Mars". These talks highlighted many interesting technological aspects of the measurements: XRF analysis is done first by the same CCD camera, which works as an energy-dispersive 2D X-ray detector, even when the main aim of the measurement is obtaining the XRD pattern. In the analysis of unknown samples, generally both chemical composition and the crystal structure are indispensable. Another reason is that XRF helps the systematic use of single photon counting mode of the CCD camera to get a good quality XRD pattern. Secondly, the samples are vibrated all the time to ensure a smooth and continuous Debye ring. The rover furthermore contains a series of standard samples to check the reliability and reproducibility of the measurements. The readers might be interested in such a compact X-ray analyzer, which combined both XRD and XRF machine. Very similar system is now commercially available. For further information on the scientific activity on Mars, visit the Web page, http://mars.jpl.nasa.gov/msl/
Professor J. Wang (University of California San Diego, USA) and his colleagues have applied X-ray fluorescence to the analysis of gunshot residue, which has been usually detected based on the analysis trace amounts of metallic and organic species deposited on the hands, face, hair, and clothing of the shooter. The researchers tried to couple square-wave stripping voltammetry (SWSV) and scanning electron microscopy (SEM) plus energy dispersive X-ray spectroscopy (EDX). The former method can be used as a rapid screening tool, while the latter contributes to confirmation of the presence of the characteristic morphology and metal composition of gunshot residue particles. For more information, see the paper, "Orthogonal Identification of Gunshot Residue with Complementary Detection Principles of Voltammetry, Scanning Electron Microscopy, and Energy-Dispersive X-ray Spectroscopy: Sample, Screen, and Confirm", A. M. O'Mahony et al., Anal. Chem., 86, 8031 (2014).
During the plenary session of the 65th Annual Denver X-Ray Conference, two awards were presented. The 2014 Birks Award was presented to George Havrilla, Los Alamos National Laboratory for his many contributions to microXRF, especially the development of the confocal XRF microscope. Dr. Havrilla has been a leader in the field of analytical XRF; including 19 years on the Denver X-ray Conference Organizing Committee; nine years as North American Editor of X-ray Spectrometry; and six years as Co-Editor-in-Chief for Advances in X-ray Analysis. The ICDD Fellow Award was presented to John Getty, Instructor in Geophysical Engineering and Principal Investigator in the Proppant Research Group at Montana Tech. John has played a key role in the planning and execution of the Denver X-ray Conference for more than 30 years. For further information, visit the Web page, http://www.dxcicdd.com/
It is now known that X-ray free-electron lasers can produce ultrafast X-ray pulses as short as 3 fs in FWHM. Scientists at the Linac Coherent Light Source (LCLS), Stanford are trying to reduce delay time errors in optical-pump & X-ray probe measurements to the 1 fs level, by 2D spectrogram measurement of the relative X-ray/optical delay. For more information, see the paper, "Sub-femtosecond precision measurement of relative X-ray arrival time for free-electron lasers", N. Hartmann et al., Nature Photonics, 8, 706 (2014).
Dr. V-D. Hodoroaba (BAM, Berlin, Germany) and his colleague have published a report on the feasibility of quantitative X-ray fluorescence (XRF) analysis using coherent (Rayleigh) and incoherent (Compton) X-ray scattering. They have evaluated the ratio of the Compton-to-Rayleigh intensity observed in XRF spectra and also have discussed its relation to the average atomic number. In so-called reference-free XRF analysis, which uses only fundamental parameters and a theoretical formula and does not rely on the calibration curve, there still exist many difficulties, particularly for matrices of lower mean atomic numbers. The analysis presented in this research has sufficiently high sensitivity to distinguish the average atomic number of specimens even within the 0.1 difference. For more information, see the paper, "Gaining Improved Chemical Composition by Exploitation of Compton-to-Rayleigh Intensity Ratio in XRF Analysis", V-D. Hodoroaba et al., Anal. Chem., 86, 6858 (2014).
far, laser combs in visible light wavelength have been known as an extremely
precise measure of dimensions. What
would happen if they move into the X-ray region? The advent of an X-ray free electron laser
(XFEL) may realize an X-ray frequency comb in the near future. Dr. S. M. Cavalettobe (Max-Planck-Institut
Lecture Date: Tuesday May 27, 2014. Dr. Johanna Nelson Weker, SLAC, delivered the SLAC public lecture, "X-rays Reveal Secret Life of Batteries" (https://www.youtube.com/watch?v=V8lSTLRkKEk)
The use of X-ray free-electrons has enabled plenty of fascinating science, such as watching non-equilibrium excited-state dynamics in complexes of 3d transition metals. Scientists at LCLS, Stanford have performed femtosecond resolution X-ray fluorescence spectroscopy, with its sensitivity to spin state, elucidating the spin crossover dynamics of [Fe(2, 2ˈ-bipyridine)3]2+ on photoinduced metal-to-ligand charge transfer excitation. For more information, see the paper, "Tracking excited-state charge and spin dynamics in iron coordination complexes", W. Zhang et al., Nature, 509, 345 (2014).
K. Binnemans (KU Leuven,
An interesting and useful tutorial on X-ray analytical methods for newcomers is now available in the Materials Today Podcast. Dr. Ravi Yellepeddi (Thermo Fisher Scientific) explains the principle of X-ray fluorescence, recent progress in instruments, and the variety of applications in industry and research laboratories. The talk is around 30 min. Visit the following Web site,
application of confocal micro-X-ray fluorescence has been reported by Dr. Tianxi
Union of Crystallography (IUCr) has announced that Professors A. Janner and T. W.
J. M. Janssen (both from the Institute for Theoretical Physics, University of
Nijmegen, The Netherlands) have been awarded the tenth Ewald prize for the
development of superspace crystallography and its application to the analysis
of aperiodic crystals. The presentation
of the Ewald Prize will be made during the Montreal Congress Opening Ceremony
on 5 August 2014. The Ewald prize
consists of a medal, a certificate and an award of USD 30,000. Former recipients are E. Dodson (UK), C.
Giacovazzo (Italy), G. M. Sheldric (Germany) in 2011, D. Sayre (
Lecture Date: Tuesday October 1, 2013. Jennifer Mass of the Winterthur Museum in Wilmington, Delaware, delivered the SLAC public lecture, "Don't Fade Away: Saving the Vivid Yellows of Matisse and Van Gogh." (https://www.youtube.com/watch?v=RiASAbniQYw)
recipient of the 8th Asada Award, which is presented by the Discussion Group of
the plenary session of the 63rd Annual Denver X-Ray Conference, three
awards were presented. The 2013 Barrett
Award was presented to Vaclav Petricek of the Institute of Physics, Academy of
Sciences of the Czech Republic, Praha, Czech Republic, for developing the
theory of incommensurate/modulated/composite crystal structures and its
implementation in the computing system Jana2006 (the most widely-used system
for solving and refining aperiodic structures), and for making possible the
correct archival of such structures in the Powder Diffraction FileTM". The 2013 Jenkins Award was presented to Rene
Van Grieken of the
The Advanced Photon Source (APS) and APS Users Organization have announced that the 2013 Arthur H. Compton Award has been presented jointly to David E. Moncton, John N. Galayda, Michael Borland, and Louis Emery. The award recognizes the recipients' visionary leadership and technical ingenuity in introducing "top-up" operation to the synchrotron radiation community. The award consists of a plaque and $2500. Former recipients of this award are: Edward Stern, Farrel Lytle, Dale Sayers (posthumously), John Rehr (2011); Simon Mochrie, Mark Sutton, Gerhard Grubel (2009); Andrzej Joachimiak, Gerold Rosenbaum (2007); Gunter Schmahl and Janos Kirz (2005); Martin Blume, Doon Gibbs, Kazumichi Namikawa, Denis McWhan (2003); Wayne A. Hendrickson (2001); Sunil K. Sinha (2000); Donald H. Bilderback, Andreas K. Freund, Gordon S. Knapp, Dennis M. Mills (1998); Philip M. Platzman, Peter M. Eisenberger (1997); Nikolai Vinokurov, Klaus Halbach (1995).