Ryosuke Tsutsumi

Osaka University, Suika, Ōsaka, Japan

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Publications (8)25.31 Total impact

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    ABSTRACT: To realize coherent x-ray diffraction microscopy with higher spatial resolution, it is necessary to increase the density of x-ray photons illuminated onto the sample. In this study, we developed a coherent x-ray diffraction apparatus with Kirkpatrick-Baez mirror optics. By using mirrors fabricated by elastic emission machining, a high-density coherent x-ray beam was produced. In a demonstration experiment using a silver nanocube as a sample, a high-contrast coherent x-ray diffraction pattern was observed over a wide-q range. This proves that both the density and the degree of coherence of the focused beam were high.
    AIP Conference Proceedings. 09/2011; 1365(1).
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    ABSTRACT: We demonstrated high-resolution element-specific diffraction microscopy using a hard X-ray beam focused by Kirkpatrick–Baez mirrors. Coherent diffraction patterns of an Au/Ag nanoparticle were measured at incident X-ray energies around the Au LIII absorption edge. By calculating the difference between the intensities of reconstructed images obtained at different energies, an image of the Au element could be derived. From the difference image, it was suggested that the replacement reaction progresses from the corners of Ag cubic particle.
    Diamond Light Source Proceedings. 04/2011; 1(SRMS-7).
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    ABSTRACT: Coherent diffraction microscopy using highly focused hard X-ray beams allows us to three-dimensionally observe thick objects with a high spatial resolution, also providing us with unique structural information, i.e., electron density distribution, not obtained by X-ray tomography with lenses, atom probe microscopy, or electron tomography. We measured high-contrast coherent X-ray diffraction patterns of a shape-controlled Au/Ag nanoparticle and successfully reconstructed a projection and a three-dimensional image of the nanoparticle with a single pixel (or a voxel) size of 4.2 nm in each dimension. The small pits on the surface and a hollow interior were clearly visible. The Au-rich regions were identified based on the electron density distribution, which provided insight into the formation of Au/Ag nanoboxes.
    Nano Letters 05/2010; 10(5):1922-6. · 13.03 Impact Factor
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    ABSTRACT: We developed a coherent x-ray diffraction microscopy (CXDM) system that enables us to precisely evaluate the electron density of an isolated sample. This system enables us to determine the dose per surface unit of x rays illuminated onto an isolated sample by combining incident x-ray intensity monitoring and the CXDM of a reference sample. By using this system, we determined the dose of x rays illuminated onto a nanostructured island fabricated by focused-ion-beam chemical vapor deposition and derived the electron density distribution of such a nanostructured island. A projection image of the nanostructured island with a spatial resolution of 24.1 nm and a contrast resolution higher than 2.3×10<sup>7</sup> electrons / pixel was successfully reconstructed.
    Review of Scientific Instruments 04/2010; · 1.60 Impact Factor
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    ABSTRACT: Hard x-ray diffraction microscopy enables us to observe thick objects at high spatial resolution. The resolution of this method is limited, in principle, by only the x-ray wavelength and the largest scattering angle recorded. As the resolution approaches the wavelength, the thickness effect of objects plays a significant role in x-ray diffraction microscopy. In this paper, we report high-resolution hard x-ray diffraction microscopy for thick objects. We used highly focused coherent x rays with a wavelength of similar to 0.1 nm as an incident beam and measured the diffraction patterns of a similar to 150-nm-thick silver nanocube at the scattering angle of similar to 3 degrees. We observed a characteristic contrast of the coherent diffraction pattern due to only the thickness effect and collected the diffraction patterns at nine incident angles so as to obtain information on a cross section of Fourier space. We reconstructed a pure projection image by the iterative phasing method from the patched diffraction pattern. The edge resolution of the reconstructed image was similar to 2 nm, which was the highest resolution so far achieved by x-ray microscopy. The present study provides us with a method for quantitatively observing thick samples at high resolution by hard x-ray diffraction microscopy.
    Physical Review B 01/2010; 82(21). · 3.66 Impact Factor
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    ABSTRACT: A method for evaluating the two-dimensional photon density distribution in focused hard X-ray beams is proposed and demonstrated in a synchrotron experiment at SPring-8. A synchrotron X-ray beam of 11.8 key is focused to a similar to 1 mu m spot by Kirkpatrick-Baez mirrors. The two-dimensional intensity distribution of the focused beam is derived by monitoring the forward diffracted intensity from an isolated silver nanocube with an edge length of similar to 150 nm positioned in the beam waist, which is two-dimensionally scanned. Furthermore, the photon density of X-rays illuminated onto the nanocube is estimated by utilizing coherent X-ray diffraction microscopy. This method is useful for evaluating the photon density distribution of hard X-ray beams focused to a spot size of less than a few micrometers. (C) 2009 Elsevier B.V. All rights reserved.
    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 01/2010; 616(2-3):266-269. · 1.14 Impact Factor
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    ABSTRACT: X-ray waves in the center of the beam waist of nearly diffraction limited focused x-ray beams can be considered to have amplitude and phase that are both almost uniform, i.e., they are x-ray plane waves. Here we report the results of an experimental demonstration of high-resolution diffraction microscopy using the x-ray plane wave of the synchrotron x-ray beam focused using Kirkpatrik-Baez mirrors. A silver nanocube with an edge length of ∼100 nm is illuminated with the x-ray beam focused to a ∼1 μm spot at 12 keV. A high-contrast symmetric diffraction pattern of the nanocube is observed in the forward far field. An image of the nanocube is successfully reconstructed by an iterative phasing method and its half-period resolution is 3.0 nm. This method does not only dramatically improve the spatial resolution of x-ray microscopy but also is a key technology for realizing single-pulse diffractive imaging using x-ray free-electron lasers.
    Physical Review B 08/2009; · 3.66 Impact Factor
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    ABSTRACT: High-flux coherent x rays are necessary for the improvement of the spatial resolution in coherent x-ray diffraction microscopy (CXDM). In this study, high-resolution CXDM using Kirkpatrick–Baez (KB) mirrors is proposed, and the mirrors are designed for experiments of the transmission scheme at SPring-8. Both the photon density and spatial coherence of synchrotron x rays focused by the KB mirrors are investigated by wave optical simulation. The KB mirrors can produce nearly diffraction-limited two-dimensional focusing x rays of ∼1 μ m in size at 8 keV . When the sample size is less than ∼1 μ m , the sample can be illuminated with full coherent x rays by adjusting the cross-slit size set between the source and the mirrors. From the estimated photon density at the sample position, the feasibility of CXDM with a sub- 1- nm spatial resolution is suggested. The present ultraprecise figuring process enables us to fabricate mirrors for carrying out high-resolution CXDM experiments.
    Journal of Applied Physics 05/2009; · 2.21 Impact Factor