Single-shot spectrometry for x-ray free-electron lasers

An experimental scheme to realize single-shot spectrometry for the diagnostics of x-ray free-electron lasers (XFELs) is presented. The combination of an ultraprecisely figured mirror and a perfect crystal form a simple, high-precision spectrometer that can cover an energy range from a few eV to a hundred eV with high resolution. The application of the spectrometer to determine XFEL pulse widths was investigated theoretically and experimentally. It has been shown that the present system can determine pulse widths from sub-fs to ps in a single shot even for spontaneous radiation. The system can be easily extended to even shorter pulses.     

Polarization control of an X‐ray free‐electron laser with a diamond phase retarder

A diamond phase retarder was applied to control the polarization states of a hard X‐ray free‐electron laser (XFEL) in the photon energy range 5–20 keV. The horizontal polarization of the XFEL beam generated from the planar undulators of the SPring‐8 Angstrom Compact Free‐Electron Laser (SACLA) was converted into vertical or circular polarization of either helicity by adjusting the angular offset of the diamond crystal from the exact Bragg condition. Using a 1.5 mm‐thick crystal, a high degree of circular polarization, 97%, was obtained for 11.56 keV monochromatic X‐rays, whereas the degree of vertical polarization was 67%, both of which agreed with the estimations including the energy bandwidth of the Si 111 beamline monochromator.     

An arrayed-window microfluidic device for observation of mixed nanoparticles with an X-ray free-electron laser

Optical Review - A microfluidic device was developed for coherent diffraction imaging using an X-ray free-electron laser (XFEL-CDI). Liquid samples, which are separately packed in reservoirs of the...     

Simulation and Experimental Study of Wavefront Measurement Accuracy of the Pencil-Beam Method

Ultra-bright and high-coherence X-rays are now being used in synchrotron radiation facilities and X-ray free electron laser facilities. X-ray focusing techniques are essential to take full advantage of these excellent X-ray light sources. To meet the strong demand, high-quality X-ray focusing optics have been developed owing to the advancement of ultraprecision machining and measurement. State-of-the-art refractive lenses [1 C.G. Schroer, Applied Physics Letters 87, 124103 (2005).[Crossref], [Web of Science ®] , [Google Scholar]], zone plates [2 T. Chen, Optics Express 19, 19919 (2011).[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]], and Laue lenses [3 H. Yan, Optics Express 19, 15069 (2011).[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]] can be used to achieve X-ray focusing to a spot a few tens of nanometers.     

Single-nanometer focusing of hard x-rays by Kirkpatrick-Baez mirrors

We have constructed an extremely precise optical system for hard-x-ray nanofocusing in a synchrotron radiation beamline. Precision multilayer mirrors were fabricated, tested, and employed as Kirkpatrick-Baez mirrors with a novel phase error compensator. In the phase compensator, an at-wavelength wavefront error sensing method based on x-ray interferometry and an in situ phase compensator mirror, which adaptively deforms with nanometer precision, were developed to satisfy the Rayleigh criterion to achieve diffraction-limited focusing in a single-nanometer range. The performance of the optics was tested at BL29XUL of SPring-8 and was confirmed to realize a spot size of approximately 7 nm.     

Time-domain interferometry experiments using multi-line nuclear absorbers

Langmuir-Blodgett (LB) films of octadecanoyl hydroxamic acid (C18N) complexed with Fe^3?+? ions have been prepared at various subphase pH values. The LB films consisting of different number of layers were investigated by ⁵⁷Fe conversion electron M?ssbauer spectroscopy (CEM) at room temperature. The CEM detector contained a piece of α-iron, enriched with ⁵⁷Fe, using as an internal standard. The M?ssbauer pattern of the C18N/Fe LB films is a doublet with parameters δ = 0.35?mm/s and Δ = 0.74?mm/s. A gradual increase of the relative occurrence of the doublet compared to the sextet of the internal standard was observed with the increasing number of layers, indicating the nearly uniform distribution of Fe among the LB layers.     

Development of 125Te synchrotron-radiation-based Mössbauer spectroscopy

The Mössbauer spectra of the 35.49 keV excited state of ¹²⁵Te were observed in the energy domain using synchrotron radiation for the first time. The obtained isomer shifts and Debye temperature agree with previous experiments. These results show that this method will be applicable to various compounds.