T. Matsushita

1-km beamline at SPring-8

A one-kilometer long synchrotron radiation beamline with an x- ray undulator source was completed at SPring-8. The beamline was planned to facilitate various applications of a wide-area coherent x-ray beam, development of bi-crystal x-ray interferometers for gravitational red-shift measurement and development of highly sensitive diagnostic methods of accelerator dynamics. This paper reports the structure of the long beamline as well as some selected first results including phase contrast imaging and diffraction imaging applications.

Real-time investigation of protein unfolding at an air-water interface at the 1 s time scale

Protein unfolding at an air–water interface is followed in real time by a recently developed simultaneous multiple-angle–wavelength-dispersive X-ray reflectometer with a time resolution of 1u2005s.

A simultaneous multiple angle-wavelength dispersive X-ray reflectometer using a bent-twisted polychromator crystal

Using a convergent X-ray beam having continuously varying energy and glancing angle as a function of direction, the whole profile of a specular X-ray reflectivity curve is measured with no need for any mechanical motion during the measurement.

Development of a high-resolution x-ray imaging system with a charge-coupled-device detector coupled with crystal x-ray magnifiers

A high-spatial-resolution x-ray imaging system for microscopic use has been developed, which utilizes a charge-coupled-device (CCD) detector as an imaging device. The spatial resolution of the x-ray CCD detector with Gd2O2S:Tb is 8.0 μm in terms of the full width at half-maximum of the line-spread function with a conversion gain of 0.58u200ae-h/xph. In order to obtain a higher spatial resolution, x-ray magnifiers based on asymmetric Si(111) Bragg reflections are placed in front of the x-ray CCD detector. The spatial resolution of this imaging system has been improved to 1.2 μm.

A method for measuring the specular X-ray reflectivity with millisecond time resolution

A method for quick measurement of the specular X-ray reflectivity using a tapered undulator source is described. It uses a convergent X-ray beam with a one-to-one correspondence between X-ray energy and direction, which is produced by diffraction of a white X-ray beam at a curved silicon crystal. To increase the momentum transfer range, the sample is rotated 45? from the horizontal around the incident beam direction, so that both the X-ray energy and the incident angle change continuously with direction. The specularly reflected beam is observed with a two-dimensional detector. The X-ray reflectivity curve in a wide momentum transfer range can be observed in a single detector exposure with a time resolution in the millisecond range. Test measurements were done for a commercial silicon wafer and a gold thin film on silicon.

Flux Growth and Characterization of α-57Fe2O3 Single Crystals for Nuclear Bragg Scattering Optical Components

57Fe-enriched hematite, α-57Fe2O3, single crystals for the X-ray optical components of nuclear Bragg scattering (NBS) have been successfully grown by the PbO-V2O5 flux method. The X-ray rocking curves for selected areas obtained by the double-crystal method reveal that the minimum value of full width at half-maximum for the rhombohedral (6 6 6)r reflection is 2.3 arcs for λ=1.12 A. Two types of imperfections, slight bending and sector zoning are observed in the crystals by precise X-ray topography and gonlometry. The maximum counting rate of NBS (14.4 eV photons) using the best crystal with (7 7 7)r reflection is as high as 20000 cps, which has been observed using the X-ray beam from the synchrotron radiation of TRISTAN, at National Laboratory for High Energy Physics (KEK), Tsukuba.

Quick X-Ray Reflectometry in the Simultaneous Multiple Angle-Wavelength Dispersive Mode

The whole profile of the specular X-ray reflectivity curve was simultaneously and quickly measured with no need to rotate the specimen, the detector or the monochromator crystal. A white synchrotron beam from a bending magnet source is incident on a bent-twisted silicon (111) crystal polychromator that produces a convergent X-ray beam with a continuously varying wavelength (energy) and glancing angle to the specimen surface. This convergent X-ray beam was specularly reflected in the vertical direction by the specimen placed at the focus. The normalized spatial distribution across the beam direction of the reflected beam represents a specular X-ray reflectivity curve because each position along the line recorded on the two dimensional detector surface corresponds to a different momentum transfer. Reflectivity curves from a (001) silicon wafer, a nickel thin film on a silicon substrate, and a water surface were measured with data collection times of 0.001-100 s, 0.01-100 s, and 1.0-1000 s, respectively. The simultaneously covered momentum transfer range was 0.03-0.52 A−1 for solid specimens and 0-0.41 A−1 for liquid specimen.

A quick convergent-beam laboratory X-ray reflectometer using a simultaneous multiple-angle dispersive geometry

An X-ray reflectometer, using a laboratory X-ray source, that can measure the specular X-ray reflectivity curve with a time resolution of 10u2005s or less was developed. Low reflectivities can be measured accurately because the background can be subtracted from the signal.

Initial Conformation of Adsorbed Proteins at an Air–Water Interface

We present the results of time-resolved X-ray reflectivity measurements carried out to investigate the early stage of protein adsorption and deformation at an air-water interface. Three globular proteins [lysozyme, myoglobin, and bovine serum albumin (BSA)] were studied, and we observed that the proteins adsorbed at the air-water interface initially possessed a thinner conformation than their native structures. The degree of deformation increased in the order myoglobin < lysozyme < BSA, which was inconsistent with the order of molecular flexibility. The initial rate of protein adsorption increased in the order lysozyme < BSA < myoglobin as determined by the dynamic surface tension. More flexible proteins generally adsorb at the interface more rapidly; however, proteins with hydrophobic patches on the protein surface, such as myoglobin, adsorb at the interface with little deformation. These results provide evidence that protein unfolding during adsorption only takes place if the kinetics of adsorption are similar to or slower than the kinetics of unfolding.

Fabrication and Characterization of Elliptically‐Curved, Laterally‐Graded Multilayers for Focusing X‐ray Polychromator Applications

We have developed a novel X‐ray multilayer working as a focusing polychromator. A multilayer mirror enables independent designs of the focal length and the spectral dispersion, and much higher throughput than the curved crystal. Our ion beam sputtering deposition apparatus has a speed programmable shuttering system for control of the lateral thickness gradient. A SiC/C and three V/C multilayers were deposited on each 150 mm long Si wafers. Period thicknesses are tuned to the designed energy of 5–12 keV, 12–19 keV, 19–26 keV and 26–33 keV, respectively. Four multilayers were clamped to form a 600 mm long 5–33 keV range elliptic mirror on a shaped Cu base plate. The focal length is 700 mm, which is large enough for setups around the sample position. The energy calibration was performed at BL‐15C of the Photon Factory based on absorption edges of metal foils, which was in good agreement with the period thickness measured by a laboratory X‐ray diffractometer.