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
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 (
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).
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.
Dr. B. Kanngießer (Technische Universität
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,
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.
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,
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,
The Science and Technology Foundation of Japan has announced that three
some readers already know Dr. Ken Lea's synchrotron song, but now it is
available on YouTube. The song is about synchrotron radiation and many
scientific studies, which have been done at The Synchrotron Radiation Source
(SRS), Daresbury Laboratory in
In Japan, a research team led by Professor K. Yamauchi (Osaka University) and Professor T. Ishikawa (Riken, Harima, Japan) has recently succeeded in focusing ultra short X-ray laser pulses from the SPring-8 Angstrom Compact free electron LAser (SACLA). With reflective optics comprising elliptically figured mirrors with nm accuracy to preserve a coherent wavefront, they have obtained a focused small beam of 0.95 × 1.20 μm2 at 10 keV. The estimated achievable power density at the sample position is 6 × 1017 W/cm2. For more information, see the paper, "Focusing of X-ray free-electron laser pulses with reflective optics", H. Yumoto et al., Nature Photonics, 7, 43 (2013).
At Linac Coherent Light Source (LCLS), Stanford, USA, a series of experimental works has been carried out based on the core-level excitation and relaxation process. One recently published paper from Stanford reports the resonant generation of Kα emission from aluminum foil (1μm thick) in a solid-plasma state created by irradiating very strong X-ray free-electron laser pulses (less than 80 fs time width, 1.6×1012 photons/pulse). In the experiment, quasimonochromatic (0.5% bandwidth) X-ray pulses in the energy range of 1480-1580 eV (below and slightly above the K edge of ground state Al) were focused onto a 3μm diameter spot on the sample, with a corresponding peak intensity in excess of 1017 W/cm2. To analyze the X-ray spectra, the research group employed a wavelength-dispersive X-ray spectrometer with a flat ADP (101) crystal and an X-ray CCD camera. Since the same atom can absorb multiple photons contained in the single pulse time width, with L-shell holes being created and leading to the excitation of a K-shell electron into one of these L-holes, the Kα X-rays are produced. The research group studied many such emission spectra produced by tuning the XFEL energy to the K-L transitions of those highly charged ions that have transition energies below the K edge of the cold material. It was also found that resonance emission peaks broaden significantly, and this was explained as opacity effects. Because of the intensity-dependent optical depth, the transparent sample at low intensity thickens optically with an intense XFEL pulse. For more information, see the paper, "Resonant Kα Spectroscopy of Solid-Density Aluminum Plasmas", B. I. Cho et al., Phys. Rev. Lett., 109, 245003 (2012).