Takahiro Sato

All Publications

• A Contrast Calibration Protocol for X-ray Speckle Visibility Spectroscopy APPLIED SCIENCES-BASEL Sun, Y., Esposito, V., Hart, P., Hansson, C., Li, H., Nakahara, K., MacArthur, J., Nelson, S., Sato, T., Song, S., Sun, P., Fuoss, P., Sutton, M., Zhu, D. 2021; 11 (21)

  View details for DOI 10.3390/app112110041

  View details for Web of Science ID 000726897500001

• Subterahertz collective dynamics of polar vortices. Nature Li, Q., Stoica, V. A., Pasciak, M., Zhu, Y., Yuan, Y., Yang, T., McCarter, M. R., Das, S., Yadav, A. K., Park, S., Dai, C., Lee, H. J., Ahn, Y., Marks, S. D., Yu, S., Kadlec, C., Sato, T., Hoffmann, M. C., Chollet, M., Kozina, M. E., Nelson, S., Zhu, D., Walko, D. A., Lindenberg, A. M., Evans, P. G., Chen, L., Ramesh, R., Martin, L. W., Gopalan, V., Freeland, J. W., Hlinka, J., Wen, H. 2021; 592 (7854): 376–80

  Abstract

  The collective dynamics of topological structures1-6 are of interest from both fundamental and applied perspectives. For example, studies of dynamical properties of magnetic vortices and skyrmions3,4 have not only deepened our understanding of many-body physics but also offered potential applications in data processing and storage7. Topological structures constructed from electrical polarization, rather than electron spin, have recently been realized in ferroelectric superlattices5,6, and these are promising for ultrafast electric-field control of topological orders. However, little is known about the dynamics underlying the functionality of such complex extended nanostructures. Here, using terahertz-field excitation and femtosecond X-ray diffraction measurements, we observe ultrafast collective polarization dynamics that are unique to polar vortices, with orders-of-magnitude higher frequencies and smaller lateral size than those of experimentally realized magnetic vortices3. A previously unseen tunable mode, hereafter referred to as a vortexon, emerges in the form of transient arrays of nanoscale circular patterns of atomic displacements, which reverse their vorticity on picosecond timescales. Its frequency is considerably reduced (softened) at a critical strain, indicating a condensation (freezing) of structural dynamics. We use first-principles-based atomistic calculations and phase-field modelling to reveal the microscopic atomic arrangements and corroborate the frequencies of the vortex modes. The discovery of subterahertz collective dynamics in polar vortices opens opportunities for electric-field-driven data processing in topological structures with ultrahigh speed and density.

  View details for DOI 10.1038/s41586-021-03342-4

  View details for PubMedID 33854251

• Visualization of dynamic polaronic strain fields in hybrid lead halide perovskites. Nature materials Guzelturk, B., Winkler, T., Van de Goor, T. W., Smith, M. D., Bourelle, S. A., Feldmann, S., Trigo, M., Teitelbaum, S. W., Steinruck, H., de la Pena, G. A., Alonso-Mori, R., Zhu, D., Sato, T., Karunadasa, H. I., Toney, M. F., Deschler, F., Lindenberg, A. M. 2021

  Abstract

  Excitation localization involving dynamic nanoscale distortions is a central aspect of photocatalysis1, quantum materials2 and molecular optoelectronics3. Experimental characterization of such distortions requires techniques sensitive to the formation of point-defect-like local structural rearrangements in real time. Here, we visualize excitation-induced strain fields in a prototypical member of the lead halide perovskites4 via femtosecond resolution diffuse X-ray scattering measurements. This enables momentum-resolved phonon spectroscopy of the locally distorted structure and reveals radially expanding nanometre-scale strain fields associated with the formation and relaxation of polarons in photoexcited perovskites. Quantitative estimates of the magnitude and shape of this polaronic distortion are obtained, providing direct insights into the dynamic structural distortions that occur in these materials5-9. Optical pump-probe reflection spectroscopy corroborates these results and shows how these large polaronic distortions transiently modify the carrier effective mass, providing a unified picture of the coupled structural and electronic dynamics that underlie the optoelectronic functionality of the hybrid perovskites.

  View details for DOI 10.1038/s41563-020-00865-5

  View details for PubMedID 33398119

• A self-referenced in-situ arrival time monitor for X-ray free-electron lasers. Scientific reports Diez, M. n., Galler, A. n., Schulz, S. n., Boemer, C. n., Coffee, R. N., Hartmann, N. n., Heider, R. n., Wagner, M. S., Helml, W. n., Katayama, T. n., Sato, T. n., Sato, T. n., Yabashi, M. n., Bressler, C. n. 2021; 11 (1): 3562

  Abstract

  We present a novel, highly versatile, and self-referenced arrival time monitor for measuring the femtosecond time delay between a hard X-ray pulse from a free-electron laser and an optical laser pulse, measured directly on the same sample used for pump-probe experiments. Two chirped and picosecond long optical supercontinuum pulses traverse the sample with a mutually fixed time delay of 970 fs, while a femtosecond X-ray pulse arrives at an instant in between both pulses. Behind the sample the supercontinuum pulses are temporally overlapped to yield near-perfect destructive interference in the absence of the X-ray pulse. Stimulation of the sample with an X-ray pulse delivers non-zero contributions at certain optical wavelengths, which serve as a measure of the relative arrival time of the X-ray pulse with an accuracy of better than 25 fs. We find an excellent agreement of our monitor with the existing timing diagnostics at the SACLA XFEL with a Pearson correlation value of 0.98. We demonstrate a high sensitivity to measure X-ray pulses with pulse energies as low as 30 [Formula: see text]J. Using a free-flowing liquid jet as interaction sample ensures the full replacement of the sample volume for each X-ray/optical event, thus enabling its utility even at MHz repetition rate XFEL sources.

  View details for DOI 10.1038/s41598-021-82597-3

  View details for PubMedID 33574378

• The ePix10k 2-megapixel hard X-ray detector at LCLS. Journal of synchrotron radiation van Driel, T. B., Nelson, S. n., Armenta, R. n., Blaj, G. n., Boo, S. n., Boutet, S. n., Doering, D. n., Dragone, A. n., Hart, P. n., Haller, G. n., Kenney, C. n., Kwaitowski, M. n., Manger, L. n., McKelvey, M. n., Nakahara, K. n., Oriunno, M. n., Sato, T. n., Weaver, M. n. 2020; 27 (Pt 3): 608–15

  Abstract

  The ePix10ka2M (ePix10k) is a new large area detector specifically developed for X-ray free-electron laser (XFEL) applications. The hybrid pixel detector was developed at SLAC to provide a hard X-ray area detector with a high dynamic range, running at the 120 Hz repetition rate of the Linac Coherent Light Source (LCLS). The ePix10k consists of 16 modules, each with 352 × 384 pixels of 100 µm × 100 µm distributed on four ASICs, resulting in a 2.16 megapixel detector, with a 16.5 cm × 16.5 cm active area and ∼80% coverage. The high dynamic range is achieved with three distinct gain settings (low, medium, high) as well as two auto-ranging modes (high-to-low and medium-to-low). Here the three fixed gain modes are evaluated. The resulting dynamic range (from single photon counting to 10000 photons pixel-1 pulse-1 at 8 keV) makes it suitable for a large number of different XFEL experiments. The ePix10k replaces the large CSPAD in operation since 2011. The dimensions of the two detectors are similar, making the upgrade from CSPAD to ePix10k straightforward for most setups, with the ePix10k improving on experimental performance. The SLAC-developed ePix cameras all utilize a similar platform, are tailored to target different experimental conditions and are designed to provide an upgrade path for future high-repetition-rate XFELs. Here the first measurements on this new ePix10k detector are presented and the performance under typical XFEL conditions evaluated during an LCLS X-ray diffuse scattering experiment measuring the 9.5 keV X-ray photons scattered from a thin liquid jet.

  View details for DOI 10.1107/S1600577520004257

  View details for PubMedID 32381760

• Speckle correlation as a monitor of X-ray free-electron laser induced crystal lattice deformation. Journal of synchrotron radiation Plumley, R. n., Sun, Y. n., Teitelbaum, S. n., Song, S. n., Sato, T. n., Chollet, M. n., Nelson, S. n., Wang, N. n., Sun, P. n., Robert, A. n., Fuoss, P. n., Sutton, M. n., Zhu, D. n. 2020; 27 (Pt 6): 1470–76

  Abstract

  X-ray free-electron lasers (X-FELs) present new opportunities to study ultrafast lattice dynamics in complex materials. While the unprecedented source brilliance enables high fidelity measurement of structural dynamics, it also raises experimental challenges related to the understanding and control of beam-induced irreversible structural changes in samples that can ultimately impact the interpretation of experimental results. This is also important for designing reliable high performance X-ray optical components. In this work, X-FEL beam-induced lattice alterations are investigated by measuring the shot-to-shot evolution of near-Bragg coherent scattering from a single crystalline germanium sample. It is shown that X-ray photon correlation analysis of sequential speckle patterns measurements can be used to monitor the nature and extent of lattice rearrangements. Abrupt, irreversible changes are observed following intermittent high-fluence monochromatic X-ray pulses, thus revealing the existence of a threshold response to X-FEL pulse intensity.

  View details for DOI 10.1107/S1600577520011509

  View details for PubMedID 33147171

• Compact hard x-ray split-delay system based on variable-gap channel-cut crystals OPTICS LETTERS Sun, Y., Wang, N., Song, S., Sun, P., Chollet, M., Sato, T., van Driel, T. B., Nelson, S., Plumley, R., Montana-Lopez, J., Teitelbaum, S. W., Haber, J., Hastings, J. B., Baron, A. R., Sutton, M., Fuoss, P. H., Robert, A., Zhu, D. 2019; 44 (10): 2582–85

  Abstract

  We present the concept and a prototypical implementation of a compact x-ray split-delay system that is capable of performing continuous on-the-fly delay scans over a range of ∼10  ps with sub-100 nanoradian pointing stability. The system consists of four channel-cut silicon crystals, two of which have gradually varying gap sizes from intentional 5 deg asymmetric cuts. The delay adjustment is realized by linear motions of these two monolithic varying-gap channel cuts, where the x-ray beam experiences pairs of anti-parallel reflections, and thus becomes less sensitive in output beam pointing to motion imperfections of the translation stages. The beam splitting is accomplished by polished crystal edges. A high degree of mutual coherence between the two branches at the focus is observed by analyzing small-angle coherent x-ray scattering patterns. We envision a wide range of applications including single-shot x-ray pulse temporal diagnostics, studies of high-intensity x-ray-matter interactions, as well as measurement of dynamics in disordered material systems using split-pulse x-ray photon correlation spectroscopy.

  View details for DOI 10.1364/OL.44.002582

  View details for Web of Science ID 000467906400050

  View details for PubMedID 31090737

• A simple instrument to find spatiotemporal overlap of optical/X-ray light at free-electron lasers. Journal of synchrotron radiation Sato, T., Glownia, J. M., Ware, M. R., Chollet, M., Nelson, S., Zhu, D. 2019; 26 (Pt 3): 647–52

  Abstract

  A compact and robust diagnostic to determine spatial and temporal overlap between X-ray free-electron laser and optical laser pulses was developed and evaluated using monochromatic X-rays from the Linac Coherent Light Source. It was used to determine temporal overlap with a resolution of 10 fs, despite the large pulse energy fluctuations of the monochromatic X-ray pulses, and covers a wide optical wavelength range from ultraviolet to near-infrared with a single configuration.

  View details for PubMedID 31074427

• Pump-probe experimental methodology at the Linac Coherent Light Source JOURNAL OF SYNCHROTRON RADIATION Glownia, J. M., Gumerlock, K., Lemke, H. T., Sato, T., Zhu, D., Chollet, M. 2019; 26: 685–91

  View details for DOI 10.1107/S160057751900225X

  View details for Web of Science ID 000467526100009

• A simple instrument to find spatiotemporal overlap of optical/X-ray light at free-electron lasers JOURNAL OF SYNCHROTRON RADIATION Sato, T., Glownia, J. M., Ware, M. R., Chollet, M., Nelson, S., Zhu, D. 2019; 26: 647–52

  View details for DOI 10.1107/S1600577519002248

  View details for Web of Science ID 000467526100005

• Pump-probe experimental methodology at the Linac Coherent Light Source. Journal of synchrotron radiation Glownia, J. M., Gumerlock, K., Lemke, H. T., Sato, T., Zhu, D., Chollet, M. 2019; 26 (Pt 3): 685–91

  Abstract

  Experimental methods that use free-electron laser (FEL) sources that can deliver short X-ray pulses below a 10 fs pulse duration and traditional optical lasers are ideal tools for pump-probe experiments. However, these new methods also come with a unique set of challenges, such as how to accurately determine temporal overlap between two sources at the femtosecond scale and how to correct for the pulse-to-pulse beam property fluctuations of the FEL light derived from the self-amplified spontaneous emission process. Over the past several years of performing pump-probe experiments at the Linac Coherent Light Source (LCLS), new methods and tools have been developed to improve the ways experimental timing is measured, monitored and scanned. The aim of this article is to present an overview of the most commonly used techniques at LCLS to perform pump-probe-type experiments.

  View details for PubMedID 31074431

• The Macromolecular Femtosecond Crystallography Instrument at the Linac Coherent Light Source JOURNAL OF SYNCHROTRON RADIATION Sierra, R. G., Batyuk, A., Sun, Z., Aquila, A., Hunter, M. S., Lane, T. J., Liang, M., Yoon, C., Alonso-Mori, R., Armenta, R., Castagna, J., Hollenbeck, M., Osier, T. O., Hayes, M., Aldrich, J., Curtis, R., Koglin, J. E., Rendahl, T., Rodriguez, E., Carbajo, S., Guillet, S., Paul, R., Hart, P., Nakahara, K., Carini, G., DeMirci, H., Dao, E., Hayes, B. M., Rao, Y. P., Chollet, M., Feng, Y., Fuller, F. D., Kupitz, C., Sato, T., Seaberg, M. H., Song, S., van Driel, T. B., Yavas, H., Zhu, D., Cohen, A. E., Wakatsuki, S., Boutet, S. 2019; 26: 346–57

  View details for DOI 10.1107/S1600577519001577

  View details for Web of Science ID 000460859600007

• Direct observation of picosecond melting and disintegration of metallic nanoparticles. Nature communications Ihm, Y. n., Cho, D. H., Sung, D. n., Nam, D. n., Jung, C. n., Sato, T. n., Kim, S. n., Park, J. n., Kim, S. n., Gallagher-Jones, M. n., Kim, Y. n., Xu, R. n., Owada, S. n., Shim, J. H., Tono, K. n., Yabashi, M. n., Ishikawa, T. n., Miao, J. n., Noh, D. Y., Song, C. n. 2019; 10 (1): 2411

  Abstract

  Despite more than a century of study, the fundamental mechanisms behind solid melting remain elusive at the nanoscale. Ultrafast phenomena in materials irradiated by intense femtosecond laser pulses have revived the interest in unveiling the puzzling processes of melting transitions. However, direct experimental validation of various microscopic models is limited due to the difficulty of imaging the internal structures of materials undergoing ultrafast and irreversible transitions. Here we overcome this challenge through time-resolved single-shot diffractive imaging using X-ray free electron laser pulses. Images of single Au nanoparticles show heterogeneous melting at the surface followed by density fluctuation deep inside the particle, which is directionally correlated to the polarization of the pumping laser. Observation of this directionality links the non-thermal electronic excitation to the thermal lattice melting, which is further verified by molecular dynamics simulations. This work provides direct evidence to the understanding of irreversible melting with an unprecedented spatiotemporal resolution.

  View details for DOI 10.1038/s41467-019-10328-4

  View details for PubMedID 31160671

• The Macromolecular Femtosecond Crystallography Instrument at the Linac Coherent Light Source. Journal of synchrotron radiation Sierra, R. G., Batyuk, A. n., Sun, Z. n., Aquila, A. n., Hunter, M. S., Lane, T. J., Liang, M. n., Yoon, C. H., Alonso-Mori, R. n., Armenta, R. n., Castagna, J. C., Hollenbeck, M. n., Osier, T. O., Hayes, M. n., Aldrich, J. n., Curtis, R. n., Koglin, J. E., Rendahl, T. n., Rodriguez, E. n., Carbajo, S. n., Guillet, S. n., Paul, R. n., Hart, P. n., Nakahara, K. n., Carini, G. n., DeMirci, H. n., Dao, E. H., Hayes, B. M., Rao, Y. P., Chollet, M. n., Feng, Y. n., Fuller, F. D., Kupitz, C. n., Sato, T. n., Seaberg, M. H., Song, S. n., van Driel, T. B., Yavas, H. n., Zhu, D. n., Cohen, A. E., Wakatsuki, S. n., Boutet, S. n. 2019; 26 (Pt 2): 346–57

  Abstract

  The Macromolecular Femtosecond Crystallography (MFX) instrument at the Linac Coherent Light Source (LCLS) is the seventh and newest instrument at the world's first hard X-ray free-electron laser. It was designed with a primary focus on structural biology, employing the ultrafast pulses of X-rays from LCLS at atmospheric conditions to overcome radiation damage limitations in biological measurements. It is also capable of performing various time-resolved measurements. The MFX design consists of a versatile base system capable of supporting multiple methods, techniques and experimental endstations. The primary techniques supported are forward scattering and crystallography, with capabilities for various spectroscopic methods and time-resolved measurements. The location of the MFX instrument allows for utilization of multiplexing methods, increasing user access to LCLS by running multiple experiments simultaneously.

  View details for PubMedID 30855242

• Frequency-selective excitation of high-wavevector phonons APPLIED PHYSICS LETTERS Teitelbaum, S. W., Henighan, T., Liu, H., Jiang, M. P., Kozina, M., Zhu, D., Chollet, M., Sato, T., Glownia, J. M., Trigo, M., Reis, D. A. 2018; 113 (17)

  View details for DOI 10.1063/1.5047447

  View details for Web of Science ID 000449145700017

• Direct Measurement of Anharmonic Decay Channels of a Coherent Phonon. Physical review letters Teitelbaum, S. W., Henighan, T., Huang, Y., Liu, H., Jiang, M. P., Zhu, D., Chollet, M., Sato, T., Murray, É. D., Fahy, S., O'Mahony, S., Bailey, T. P., Uher, C., Trigo, M., Reis, D. A. 2018; 121 (12): 125901

  Abstract

  We report channel-resolved measurements of the anharmonic coupling of the coherent A_{1g} phonon in photoexcited bismuth to pairs of high wave vector acoustic phonons. The decay of a coherent phonon can be understood as a parametric resonance process whereby the atomic displacement periodically modulates the frequency of a broad continuum of modes. This coupling drives temporal oscillations in the phonon mean-square displacements at the A_{1g} frequency that are observed across the Brillouin zone by femtosecond x-ray diffuse scattering. We extract anharmonic coupling constants between the A_{1g} and several representative decay channels that are within an order of magnitude of density functional perturbation theory calculations.

  View details for DOI 10.1103/PhysRevLett.121.125901

  View details for PubMedID 30296113

• Direct Measurement of Anharmonic Decay Channels of a Coherent Phonon PHYSICAL REVIEW LETTERS Teitelbaum, S. W., Henighan, T., Huang, Y., Liu, H., Jiang, M. P., Zhu, D., Chollet, M., Sato, T., Murray, E. D., Fahy, S., O'Mahony, S., Bailey, T. P., Uher, C., Trigo, M., Reis, D. A. 2018; 121 (12)

  View details for DOI 10.1103/PhysRevLett.121.125901

  View details for Web of Science ID 000445177300013

• Coherent X-rays reveal the influence of cage effects on ultrafast water dynamics NATURE COMMUNICATIONS Perakis, F., Camisasca, G., Lane, T. J., Spah, A., Wikfeldt, K., Sellberg, J. A., Lehmkuehler, F., Pathak, H., Kim, K., Amann-Winkel, K., Schreck, S., Song, S., Sato, T., Sikorski, M., Eilert, A., McQueen, T., Ogasawara, H., Nordlund, D., Roseker, W., Koralek, J., Nelson, S., Hart, P., Alonso-Mori, R., Feng, Y., Zhu, D., Robert, A., Gruebel, G., Pettersson, L. M., Nilsson, A. 2018; 9: 1917

  Abstract

  The dynamics of liquid water feature a variety of time scales, ranging from extremely fast ballistic-like thermal motion, to slower molecular diffusion and hydrogen-bond rearrangements. Here, we utilize coherent X-ray pulses to investigate the sub-100 fs equilibrium dynamics of water from ambient conditions down to supercooled temperatures. This novel approach utilizes the inherent capability of X-ray speckle visibility spectroscopy to measure equilibrium intermolecular dynamics with lengthscale selectivity, by measuring oxygen motion in momentum space. The observed decay of the speckle contrast at the first diffraction peak, which reflects tetrahedral coordination, is attributed to motion on a molecular scale within the first 120 fs. Through comparison with molecular dynamics simulations, we conclude that the slowing down upon cooling from 328 K down to 253 K is not due to simple thermal ballistic-like motion, but that cage effects play an important role even on timescales over 25 fs due to hydrogen-bonding.

  View details for PubMedID 29765052

• State-selective preparation of Ar2+ and Kr2+ by resonantly enhanced two-photon double ionization via intermediate Rydberg states using high-order harmonics PHYSICAL REVIEW A Yamada, K., Iwasaki, A., Sato, T., Midorikawa, K., Yamanouchi, K. 2016; 94 (5)

  View details for DOI 10.1103/PhysRevA.94.053414

  View details for Web of Science ID 000387881800014

• Angular dependence of ionization probability of C2H2 in a linearly polarized intense laser field CHEMICAL PHYSICS LETTERS Hasegawa, H., Ikeda, Y., Sonoda, K., Sato, T., Iwasaki, A., Yamanouchi, K. 2016; 662: 235–39

  View details for DOI 10.1016/j.cplett.2016.09.024

  View details for Web of Science ID 000386860900041

• A beam branching method for timing and spectral characterization of hard X-ray free-electron lasers STRUCTURAL DYNAMICS-US Katayama, T., Owada, S., Togashi, T., Ogawa, K., Karvinen, P., Vartiainen, I., Eronen, A., David, C., Sato, T., Nakajima, K., Joti, Y., Yumoto, H., Ohashi, H., Yabashi, M. 2016; 3 (3): 034301

  Abstract

  We report a method for achieving advanced photon diagnostics of x-ray free-electron lasers (XFELs) under a quasi-noninvasive condition by using a beam-splitting scheme. Here, we used a transmission grating to generate multiple branches of x-ray beams. One of the two primary diffracted branches (+1st-order) is utilized for spectral measurement in a dispersive scheme, while the other (-1st-order) is dedicated for arrival timing diagnostics between the XFEL and the optical laser pulses. The transmitted x-ray beam (0th-order) is guided to an experimental station. To confirm the validity of this timing-monitoring scheme, we measured the correlation between the arrival timings of the -1st and 0th branches. The observed error was as small as 7.0 fs in root-mean-square. Our result showed the applicability of the beam branching scheme to advanced photon diagnostics, which will further enhance experimental capabilities of XFEL.

  View details for PubMedID 26958586

• Sub-nanometre resolution of atomic motion during electronic excitation in phase-change materials SCIENTIFIC REPORTS Mitrofanov, K. V., Fons, P., Makino, K., Terashima, R., Shimada, T., Kolobov, A. V., Tominaga, J., Bragaglia, V., Giussani, A., Calarco, R., Riechert, H., Sato, T., Katayama, T., Ogawa, K., Togashi, T., Yabashi, M., Wall, S., Brewe, D., Hase, M. 2016; 6: 20633

  Abstract

  Phase-change materials based on Ge-Sb-Te alloys are widely used in industrial applications such as nonvolatile memories, but reaction pathways for crystalline-to-amorphous phase-change on picosecond timescales remain unknown. Femtosecond laser excitation and an ultrashort x-ray probe is used to show the temporal separation of electronic and thermal effects in a long-lived (>100 ps) transient metastable state of Ge2Sb2Te5 with muted interatomic interaction induced by a weakening of resonant bonding. Due to a specific electronic state, the lattice undergoes a reversible nondestructive modification over a nanoscale region, remaining cold for 4 ps. An independent time-resolved x-ray absorption fine structure experiment confirms the existence of an intermediate state with disordered bonds. This newly unveiled effect allows the utilization of non-thermal ultra-fast pathways enabling artificial manipulation of the switching process, ultimately leading to a redefined speed limit, and improved energy efficiency and reliability of phase-change memory technologies.

  View details for PubMedID 26868451

• Observation of femtosecond X-ray interactions with matter using an X-ray-X-ray pump-probe scheme PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Inoue, I., Inubushi, Y., Sato, T., Tono, K., Katayama, T., Kameshima, T., Ogawa, K., Togashi, T., Owada, S., Amemiya, Y., Tanaka, T., Hara, T., Yabashi, M. 2016; 113 (6): 1492–97

  Abstract

  Resolution in the X-ray structure determination of noncrystalline samples has been limited to several tens of nanometers, because deep X-ray irradiation required for enhanced resolution causes radiation damage to samples. However, theoretical studies predict that the femtosecond (fs) durations of X-ray free-electron laser (XFEL) pulses make it possible to record scattering signals before the initiation of X-ray damage processes; thus, an ultraintense X-ray beam can be used beyond the conventional limit of radiation dose. Here, we verify this scenario by directly observing femtosecond X-ray damage processes in diamond irradiated with extraordinarily intense (∼10(19) W/cm(2)) XFEL pulses. An X-ray pump-probe diffraction scheme was developed in this study; tightly focused double-5-fs XFEL pulses with time separations ranging from sub-fs to 80 fs were used to excite (i.e., pump) the diamond and characterize (i.e., probe) the temporal changes of the crystalline structures through Bragg reflection. It was found that the pump and probe diffraction intensities remain almost constant for shorter time separations of the double pulse, whereas the probe diffraction intensities decreased after 20 fs following pump pulse irradiation due to the X-ray-induced atomic displacement. This result indicates that sub-10-fs XFEL pulses enable conductions of damageless structural determinations and supports the validity of the theoretical predictions of ultraintense X-ray-matter interactions. The X-ray pump-probe scheme demonstrated here would be effective for understanding ultraintense X-ray-matter interactions, which will greatly stimulate advanced XFEL applications, such as atomic structure determination of a single molecule and generation of exotic matters with high energy densities.

  View details for PubMedID 26811449

• A scintillator fabricated by solid-state-diffusion bonding for high-spatial resolution X-ray imaging Kameshima, T., Sato, T., Kudo, T., Ono, S., Ozaki, K., Katayama, T., Hatsui, T., Yabashi, M., Shen, Q., Nelson, C. AMER INST PHYSICS. 2016

  View details for DOI 10.1063/1.4952905

  View details for Web of Science ID 000383222800126

• Visualizing the non-equilibrium dynamics of photoinduced intramolecular electron transfer with femtosecond X-ray pulses NATURE COMMUNICATIONS Canton, S. E., Kjaer, K. S., Vanko, G., van Driel, T. B., Adachi, S., Bordage, A., Bressler, C., Chabera, P., Christensen, M., Dohn, A. O., Galler, A., Gawelda, W., Gosztola, D., Haldrup, K., Harlang, T., Liu, Y., Moller, K. B., Nemeth, Z., Nozawa, S., Papai, M., Sato, T., Sato, T., Suarez-Alcantara, K., Togashi, T., Tono, K., Uhlig, J., Vithanage, D. A., Warnmark, K., Yabashi, M., Zhang, J., Sundstrom, V., Nielsen, M. M. 2015; 6: 6359

  Abstract

  Ultrafast photoinduced electron transfer preceding energy equilibration still poses many experimental and conceptual challenges to the optimization of photoconversion since an atomic-scale description has so far been beyond reach. Here we combine femtosecond transient optical absorption spectroscopy with ultrafast X-ray emission spectroscopy and diffuse X-ray scattering at the SACLA facility to track the non-equilibrated electronic and structural dynamics within a bimetallic donor-acceptor complex that contains an optically dark centre. Exploiting the 100-fold increase in temporal resolution as compared with storage ring facilities, these measurements constitute the first X-ray-based visualization of a non-equilibrated intramolecular electron transfer process over large interatomic distances. Experimental and theoretical results establish that mediation through electronically excited molecular states is a key mechanistic feature. The present study demonstrates the extensive potential of femtosecond X-ray techniques as diagnostics of non-adiabatic electron transfer processes in synthetic and biological systems, and some directions for future studies, are outlined.

  View details for PubMedID 25727920

• Direct observation of bond formation in solution with femtosecond X-ray scattering NATURE Kim, K., Kim, J., Nozawa, S., Sato, T., Oang, K., Kim, T., Ki, H., Jo, J., Park, S., Song, C., Sato, T., Ogawa, K., Togashi, T., Tono, K., Yabashi, M., Ishikawa, T., Kim, J., Ryoo, R., Kim, J., Ihee, H., Adachi, S. 2015; 518 (7539): 385–89

  Abstract

  The making and breaking of atomic bonds are essential processes in chemical reactions. Although the ultrafast dynamics of bond breaking have been studied intensively using time-resolved techniques, it is very difficult to study the structural dynamics of bond making, mainly because of its bimolecular nature. It is especially difficult to initiate and follow diffusion-limited bond formation in solution with ultrahigh time resolution. Here we use femtosecond time-resolved X-ray solution scattering to visualize the formation of a gold trimer complex, [Au(CN)2(-)]3 in real time without the limitation imposed by slow diffusion. This photoexcited gold trimer, which has weakly bound gold atoms in the ground state, undergoes a sequence of structural changes, and our experiments probe the dynamics of individual reaction steps, including covalent bond formation, the bent-to-linear transition, bond contraction and tetramer formation with a time resolution of ∼500 femtoseconds. We also determined the three-dimensional structures of reaction intermediates with sub-ångström spatial resolution. This work demonstrates that it is possible to track in detail and in real time the structural changes that occur during a chemical reaction in solution using X-ray free-electron lasers and advanced analysis of time-resolved solution scattering data.

  View details for PubMedID 25693570

• Intense Field Ionization of C2H2 and (CCH2)-C-12-C-13 Aligned in Field-Free Space Hasegawa, H., Ikeda, Y., Sonoda, K., Sato, T., Iwasaki, A., Yamanouchi, K., Yamanouchi, Cundiff, S., DeVivieRiedle, R., KuwataGonokami, M., DiMauro, L. SPRINGER-VERLAG BERLIN. 2015: 143–46

  View details for DOI 10.1007/978-3-319-13242-6_34

  View details for Web of Science ID 000357738800034

• Highly efficient arrival timing diagnostics for femtosecond X-ray and optical laser pulses Applied Physics Express Sato, T., Togashi, T., Ogawa, K., Katayama, T., Inubushi, Y., Tono, K., Yabashi, M. 2015; 8 (1)

  View details for DOI 10.7567/APEX.8.012702

  View details for Web of Science ID 000348959300009

• Ionization of Aligned O-2 by Intense Laser Pulse Sonoda, K., Hasegawa, H., Sato, T., Iwasaki, A., Yamanouchi, K., Yamanouchi, Cundiff, S., DeVivieRiedle, R., KuwataGonokami, M., DiMauro, L. SPRINGER-VERLAG BERLIN. 2015: 147–49

  View details for DOI 10.1007/978-3-319-13242-6_35

  View details for Web of Science ID 000357738800035

• Single-shot three-dimensional structure determination of nanocrystals with femtosecond X-ray free-electron laser pulses NATURE COMMUNICATIONS Xu, R., Jiang, H., Song, C., Rodriguez, J. A., Huang, Z., Chen, C., Nam, D., Park, J., Gallagher-Jones, M., Kim, S., Kim, S., Suzuki, A., Takayama, Y., Oroguchi, T., Takahashi, Y., Fan, J., Zou, Y., Hatsui, T., Inubushi, Y., Kameshima, T., Yonekura, K., Tono, K., Togashi, T., Sato, T., Yamamoto, M., Nakasako, M., Yabashi, M., Ishikawa, T., Miao, J. 2014; 5: 4061

  Abstract

  Conventional three-dimensional (3D) structure determination methods require either multiple measurements at different sample orientations or a collection of serial sections through a sample. Here we report the experimental demonstration of single-shot 3D structure determination of an object; in this case, individual gold nanocrystals at ~5.5 nm resolution using ~10 fs X-ray free-electron laser pulses. Coherent diffraction patterns are collected from high-index-faceted nanocrystals, each struck by an X-ray free-electron laser pulse. Taking advantage of the symmetry of the nanocrystal and the curvature of the Ewald sphere, we reconstruct the 3D structure of each nanocrystal from a single-shot diffraction pattern. By averaging a sufficient number of identical nanocrystals, this method may be used to determine the 3D structure of nanocrystals at atomic resolution. As symmetry exists in many virus particles, this method may also be applied to 3D structure studies of such particles at nanometer resolution on femtosecond time scales.

  View details for PubMedID 24898682

• Time-Resolved Coherent Diffraction of Ultrafast Structural Dynamics in a Single Nanowire NANO LETTERS Newton, M. C., Sao, M., Fujisawa, Y., Onitsuka, R., Kawaguchi, T., Tokuda, K., Sato, T., Togashi, T., Yabashi, M., Ishikawa, T., Ichitsubo, T., Matsubara, E., Tanaka, Y., Nishino, Y. 2014; 14 (5): 2413–18

  Abstract

  The continuing effort to utilize the unique properties present in a number of strongly correlated transition metal oxides for novel device applications has led to intense study of their transitional phase state behavior. Here we report on time-resolved coherent X-ray diffraction measurements on a single vanadium dioxide nanocrystal undergoing a solid-solid phase transition, using the SACLA X-ray Free Electron Laser (XFEL) facility. We observe an ultrafast transition from monoclinic to tetragonal crystal structure in a single vanadium dioxide nanocrystal. Our findings demonstrate that the structural change occurs in a number of distinct stages attributed to differing expansion modes of vanadium atom pairs.

  View details for DOI 10.1021/nl500072d

  View details for Web of Science ID 000336074800027

  View details for PubMedID 24742218

• Generation of 10(20) Wcm (-2) hard X- ray laser pulses with two-stage reflective focusing system NATURE COMMUNICATIONS Mimura, H., Yumoto, H., Matsuyama, S., Koyama, T., Tono, K., Inubushi, Y., Togashi, T., Sato, T., Kim, J., Fukui, R., Sano, Y., Yabashi, M., Ohashi, H., Ishikawa, T., Yamauchi, K. 2014; 5: 3539

  Abstract

  Intense X-ray fields produced with hard X-ray free-electron laser (XFEL) have made possible the study of nonlinear X-ray phenomena. However, the observable phenomena are still limited by the power density. Here, we present a two-stage focusing system consisting of ultra-precise mirrors, which can generate an extremely intense X-ray field. The XFEL beam, enlarged with upstream optics, is focused with downstream optics that have high numerical aperture. A grating interferometer is used to monitor the wavefront to achieve optimum focusing. Finally, we generate an extremely small spot of 30 × 55 nm with an extraordinary power density of over 1 × 10(20) W cm(-2) using 9.9 keV XFEL light. The achieved power density provides novel opportunities to elucidate unexplored nonlinear phenomena in the X-ray region, which will advance development on quantum X-ray optics, astronomical physics and high-energy density science.

  View details for PubMedID 24781443

• Multiple application X-ray imaging chamber for single-shot diffraction experiments with femtosecond X-ray laser pulses JOURNAL OF APPLIED CRYSTALLOGRAPHY Song, C., Tono, K., Park, J., Ebisu, T., Kim, S., Shimada, H., Kim, S., Gallagher-Jones, M., Nam, D., Sato, T., Togashi, T., Ogawa, K., Joti, Y., Kameshima, T., Ono, S., Hatsui, T., Iwata, S., Yabashi, M., Ishikawa, T. 2014; 47: 188–97

  View details for DOI 10.1107/S1600576713029944

  View details for Web of Science ID 000330485100026

• Development of split-delay x-ray optics using Si(220) crystals at SACLA Osaka, T., Hirano, T., Yabashi, M., Sano, Y., Tono, K., Inubushi, Y., Sato, T., Ogawa, K., Matsuyama, S., Ishikawa, T., Yamauchi, K., HauRiege, S. P., Moeller, S. P., Yabashi, M. SPIE-INT SOC OPTICAL ENGINEERING. 2014

  View details for DOI 10.1117/12.2060238

  View details for Web of Science ID 000343910300004

• Two-colour hard X-ray free-electron laser with wide tunability NATURE COMMUNICATIONS Hara, T., Inubushi, Y., Katayama, T., Sato, T., Tanaka, H., Tanaka, T., Togashi, T., Togawa, K., Tono, K., Yabashi, M., Ishikawa, T. 2013; 4: 2919

  Abstract

  Ultrabrilliant, femtosecond X-ray pulses from X-ray free-electron lasers (XFELs) have promoted the investigation of exotic interactions between intense X-rays and matters, and the observation of minute targets with high spatio-temporal resolution. Although a single X-ray beam has been utilized for these experiments, the use of multiple beams with flexible and optimum beam parameters should drastically enhance the capability and potentiality of XFELs. Here we show a new light source of a two-colour double-pulse (TCDP) XFEL in hard X-rays using variable-gap undulators, which realizes a large and flexible wavelength separation of more than 30% with an ultraprecisely controlled time interval in the attosecond regime. Together with sub-10-fs pulse duration and multi-gigawatt peak powers, the TCDP scheme enables us to elucidate X-ray-induced ultrafast transitions of electronic states and structures, which will significantly contribute to the advancement of ultrafast chemistry, plasma and astronomical physics, and quantum X-ray optics.

  View details for PubMedID 24301682

• Femtosecond x-ray absorption spectroscopy with hard x-ray free electron laser APPLIED PHYSICS LETTERS Katayama, T., Inubushi, Y., Obara, Y., Sato, T., Togashi, T., Tono, K., Hatsui, T., Kameshima, T., Bhattacharya, A., Ogi, Y., Kurahashi, N., Misawa, K., Suzuki, T., Yabashi, M. 2013; 103 (13)

  View details for DOI 10.1063/1.4821108

  View details for Web of Science ID 000325284500005

• Time-interleaved multienergy acceleration for an x-ray free-electron laser facility PHYSICAL REVIEW SPECIAL TOPICS-ACCELERATORS AND BEAMS Hara, T., Tamasaku, K., Asaka, T., Inagaki, T., Inubushi, Y., Katayama, T., Kondo, C., Maesaka, H., Matsubara, S., Ohshima, T., Otake, Y., Sakurai, T., Sato, T., Tanaka, H., Togashi, T., Togawa, K., Tono, K., Yabashi, M., Ishikawa, T. 2013; 16 (8)

  View details for DOI 10.1103/PhysRevSTAB.16.080701

  View details for Web of Science ID 000323320500001

• Double Core-Hole Creation by Sequential Attosecond Photoionization PHYSICAL REVIEW LETTERS Tamasaku, K., Nagasono, M., Iwayama, H., Shigemasa, E., Inubushi, Y., Tanaka, T., Tono, K., Togashi, T., Sato, T., Katayama, T., Kameshima, T., Hatsui, T., Yabashi, M., Ishikawa, T. 2013; 111 (4): 043001

  Abstract

  X-ray fluorescence spectroscopy demonstrates that a single core-hole krypton with a 170-as lifetime can be photoionized again to a double core-hole state by an intense x-ray pulse. The observation indicates that unconventional interaction between intense x rays and atoms is no more negligible in applications with x-ray free-electron lasers. Quantitative analysis of the double core-hole creation including effects of a pulsed and spiky temporal structure enables estimation of the x-ray pulse duration in the sub-10-fs range.

  View details for PubMedID 23931361

• Investigation of ablation thresholds of optical materials using 1-mu m-focusing beam at hard X-ray free electron laser OPTICS EXPRESS Koyama, T., Yumoto, H., Senba, Y., Tono, K., Sato, T., Togashi, T., Inubushi, Y., Katayama, T., Kim, J., Matsuyama, S., Mimura, H., Yabashi, M., Yamauchi, K., Ohashi, H., Ishikawa, T. 2013; 21 (13): 15382–88

  Abstract

  We evaluated the ablation thresholds of optical materials by using hard X-ray free electron laser. A 1-µm-focused beam with 10-keV of photon energy from SPring-8 Angstrom Compact free electron LAser (SACLA) was irradiated onto silicon and SiO2 substrates, as well as the platinum and rhodium thin films on these substrates, which are widely used for optical materials such as X-ray mirrors. We designed and installed a dedicated experimental chamber for the irradiation experiments. For the silicon substrate irradiated at a high fluence, we observed strong mechanical cracking at the surface and a deep ablation hole with a straight side wall. We confirmed that the ablation thresholds of uncoated silicon and SiO2 substrates agree with the melting doses of these materials, while those of the substrates under the metal coating layer are significantly reduced. The ablation thresholds obtained here are useful criteria in designing optics for hard X-ray free electron lasers.

  View details for DOI 10.1364/OE.21.015382

  View details for Web of Science ID 000321288400046

  View details for PubMedID 23842324

• Beamline mirrors and monochromator for X-ray free electron laser of SACLA Ohashi, H., Yabashi, M., Tono, K., Inubushi, Y., Sato, T., Togashi, T., Senba, Y., Koyama, T., Yumoto, H., Miyokawa, K., Ohsawa, T., Goto, S., Ishikawa, T. ELSEVIER SCIENCE BV. 2013: 139–42

  View details for DOI 10.1016/j.nima.2012.10.094

  View details for Web of Science ID 000318128600026

• Anomalous signal from S atoms in protein crystallographic data from an X-ray free-electron laser ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY Barends, T. M., Foucar, L., Shoeman, R. L., Bari, S., Epp, S. W., Hartmann, R., Hauser, G., Huth, M., Kieser, C., Lomb, L., Motomura, K., Nagaya, K., Schmidt, C., Strecker, R., Anielski, D., Boll, R., Erk, B., Fukuzawa, H., Hartmann, E., Hatsui, T., Holl, P., Inubushi, Y., Ishikawa, T., Kassemeyer, S., Kaiser, C., Koeck, F., Kunishima, N., Kurka, M., Rolles, D., Rudek, B., Rudenko, A., Sato, T., Schroeter, C., Soltau, H., Strueder, L., Tanaka, T., Togashi, T., Tono, K., Ullrich, J., Yase, S., Wada, S., Yao, M., Yabashi, M., Ueda, K., Schlichting, I. 2013; 69: 838–42

  Abstract

  X-ray free-electron lasers (FELs) enable crystallographic data collection using extremely bright femtosecond pulses from microscopic crystals beyond the limitations of conventional radiation damage. This diffraction-before-destruction approach requires a new crystal for each FEL shot and, since the crystals cannot be rotated during the X-ray pulse, data collection requires averaging over many different crystals and a Monte Carlo integration of the diffraction intensities, making the accurate determination of structure factors challenging. To investigate whether sufficient accuracy can be attained for the measurement of anomalous signal, a large data set was collected from lysozyme microcrystals at the newly established `multi-purpose spectroscopy/imaging instrument' of the SPring-8 Ångstrom Compact Free-Electron Laser (SACLA) at RIKEN Harima. Anomalous difference density maps calculated from these data demonstrate that serial femtosecond crystallography using a free-electron laser is sufficiently accurate to measure even the very weak anomalous signal of naturally occurring S atoms in a protein at a photon energy of 7.3 keV.

  View details for DOI 10.1107/S0907444913002448

  View details for Web of Science ID 000318240200018

  View details for PubMedID 23633593

• Time-resolved Bragg coherent X-ray diffraction revealing ultrafast lattice dynamics in nano-thickness crystal layer using X-ray free electron laser JOURNAL OF THE CERAMIC SOCIETY OF JAPAN Tanaka, Y., Ito, K., Nakatani, T., Onitsuka, R., Newton, M., Sato, T., Togashi, T., Yabashi, M., Kawaguchi, T., Shimada, K., Tokuda, K., Takahashi, I., Ichitsubo, T., Matsubara, E., Nishino, Y. 2013; 121 (1411): 283–86

  View details for DOI 10.2109/jcersj2.121.283

  View details for Web of Science ID 000316771200006

• A Bragg beam splitter for hard x-ray free-electron lasers OPTICS EXPRESS Osaka, T., Yabashi, M., Sano, Y., Tono, K., Inubushi, Y., Sato, T., Matsuyama, S., Ishikawa, T., Yamauchi, K. 2013; 21 (3): 2823–31

  Abstract

  We report a Bragg beam splitter developed for utilization of hard x-ray free-electron lasers. The splitter is based on an ultrathin silicon crystal operating in the symmetric Bragg geometry to provide high reflectivity and transmissivity simultaneously. We fabricated frame-shaped Si(511) and (110) crystals with thicknesses below 10 μm by a reactive dry etching method using atmospheric-pressure plasma. The thickness variation over an illuminated area is less than 300 nm peak-to-valley. High crystalline perfection was verified by topographic and diffractometric measurements. The crystal thickness was evaluated from the period of the Pendellösung beats measured with a highly monochromatic and collimated x-ray probe. The crystals provide two replica pulses with uniform wavefront [(<1/50)λ] and low spatial intensity variation (<5%). These Bragg beam splitters will play an important role in innovating XFEL applications.

  View details for DOI 10.1364/OE.21.002823

  View details for Web of Science ID 000315991400029

  View details for PubMedID 23481739

• Thin crystal development and applications for hard x-ray free-electron lasers Osaka, T., Yabashi, M., Sano, Y., Tono, K., Inubushi, Y., Sato, T., Ogawa, K., Matsuyama, S., Ishikawa, T., Yamauchi, K., Khounsary, A., Goto, S., Morawe, C. SPIE-INT SOC OPTICAL ENGINEERING. 2013

  View details for DOI 10.1117/12.2023465

  View details for Web of Science ID 000326748800002

• Focusing of X-ray free-electron laser pulses with reflective optics NATURE PHOTONICS Yumoto, H., Mimura, H., Koyama, T., Matsuyama, S., Tono, K., Togashi, T., Inubushi, Y., Sato, T., Tanaka, T., Kimura, T., Yokoyama, H., Kim, J., Sano, Y., Hachisu, Y., Yabashi, M., Ohashi, H., Ohmori, H., Ishikawa, T., Yamauchi, K. 2013; 7 (1): 43–47

  View details for DOI 10.1038/NPHOTON.2012.306

  View details for Web of Science ID 000312835200012

• Development of ultrafast pump and probe experimental system at SACLA Sato, T., Togashi, T., Tono, K., Inubushi, Y., Tomizawa, H., Tanaka, Y., Adachi, S., Nakamura, K., Kodama, R., Yabashi, M., Susini, J., Dumas, P. IOP PUBLISHING LTD. 2013

  View details for DOI 10.1088/1742-6596/425/9/092009

  View details for Web of Science ID 000320403700154

• Determination of the Pulse Duration of an X-Ray Free Electron Laser Using Highly Resolved Single-Shot Spectra PHYSICAL REVIEW LETTERS Inubushi, Y., Tono, K., Togashi, T., Sato, T., Hatsui, T., Kameshima, T., Togawa, K., Hara, T., Tanaka, T., Tanaka, H., Ishikawa, T., Yabashi, M. 2012; 109 (14): 144801

  Abstract

  We determined the pulse duration of x-ray free electron laser light at 10 keV using highly resolved single-shot spectra, combined with an x-ray free electron laser simulation. Spectral profiles, which were measured with a spectrometer composed of an ultraprecisely figured elliptical mirror and an analyzer flat crystal of silicon (555), changed markedly when we varied the compression strength of the electron bunch. The analysis showed that the pulse durations were reduced from 31 to 4.5 fs for the strongest compression condition. The method, which is readily applicable to evaluate shorter pulse durations, provides a firm basis for the development of femtosecond to attosecond sciences in the x-ray region.

  View details for PubMedID 23083249

• A compact X-ray free-electron laser emitting in the sub-angstrom region NATURE PHOTONICS Ishikawa, T., Aoyagi, H., Asaka, T., Asano, Y., Azumi, N., Bizen, T., Ego, H., Fukami, K., Fukui, T., Furukawa, Y., Goto, S., Hanaki, H., Hara, T., Hasegawa, T., Hatsui, T., Higashiya, A., Hirono, T., Hosoda, N., Ishii, M., Inagaki, T., Inubushi, Y., Itoga, T., Joti, Y., Kago, M., Kameshima, T., Kimura, H., Kirihara, Y., Kiyomichi, A., Kobayashi, T., Kondo, C., Kudo, T., Maesaka, H., Marechal, X. M., Masuda, T., Matsubara, S., Matsumoto, T., Matsushita, T., Matsui, S., Nagasono, M., Nariyama, N., Ohashi, H., Ohata, T., Ohshima, T., Ono, S., Otake, Y., Saji, C., Sakurai, T., Sato, T., Sawada, K., Seike, T., Shirasawa, K., Sugimoto, T., Suzuki, S., Takahashi, S., Takebe, H., Takeshita, K., Tamasaku, K., Tanaka, H., Tanaka, R., Tanaka, T., Togashi, T., Togawa, K., Tokuhisa, A., Tomizawa, H., Tono, K., Wu, S., Yabashi, M., Yamaga, M., Yamashita, A., Yanagida, K., Zhang, C., Shintake, T., Kitamura, H., Kumagai, N. 2012; 6 (8): 540–44

  View details for DOI 10.1038/nphoton.2012.141

  View details for Web of Science ID 000307046800014

• A photodiode amplifier system for pulse-by-pulse intensity measurement of an x-ray free electron laser REVIEW OF SCIENTIFIC INSTRUMENTS Kudo, T., Tono, K., Yabashi, M., Togashi, T., Sato, T., Inubushi, Y., Omodani, M., Kirihara, Y., Matsushita, T., Kobayashi, K., Yamaga, M., Uchiyama, S., Hatsui, T. 2012; 83 (4): 043108

  Abstract

  We have developed a single-shot intensity-measurement system using a silicon positive-intrinsic-negative (PIN) photodiode for x-ray pulses from an x-ray free electron laser. A wide dynamic range (10(3)-10(11) photons/pulse) and long distance signal transmission (>100 m) were required for this measurement system. For this purpose, we developed charge-sensitive and shaping amplifiers, which can process charge pulses with a wide dynamic range and variable durations (ns-μs) and charge levels (pC-μC). Output signals from the amplifiers were transmitted to a data acquisition system through a long cable in the form of a differential signal. The x-ray pulse intensities were calculated from the peak values of the signals by a waveform fitting procedure. This system can measure 10(3)-10(9) photons/pulse of ~10 keV x-rays by direct irradiation of a silicon PIN photodiode, and from 10(7)-10(11) photons/pulse by detecting the x-rays scattered by a diamond film using the silicon PIN photodiode. This system gives a relative accuracy of ~10(-3) with a proper gain setting of the amplifiers for each measurement. Using this system, we succeeded in detecting weak light at the developmental phase of the light source, as well as intense light during lasing of the x-ray free electron laser.

  View details for DOI 10.1063/1.3701713

  View details for Web of Science ID 000303415300009

  View details for PubMedID 22559516

• Determination of the absolute two-photon ionization cross section of He by an XUV free electron laser JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS Sato, T., Iwasaki, A., Ishibashi, K., Okino, T., Yamanouchi, K., Adachi, J., Yagishita, A., Yazawa, H., Kannari, F., Aoyma, M., Yamakawa, K., Midorikawa, K., Nakano, H., Yabashi, M., Nagasono, M., Higashiya, A., Ishikawa, T. 2011; 44 (16)

  View details for DOI 10.1088/0953-4075/44/16/161001

  View details for Web of Science ID 000294890800001

• Extreme ultraviolet free electron laser seeded with high-order harmonic of Ti:sapphire laser OPTICS EXPRESS Togashi, T., Takahashi, E. J., Midorikawa, K., Aoyama, M., Yamakawa, K., Sato, T., Iwasaki, A., Owada, S., Okino, T., Yamanouchi, K., Kannari, F., Yagishita, A., Nakano, H., Couprie, M. E., Fukami, K., Hatsui, T., Hara, T., Kameshima, T., Kitamura, H., Kumagai, N., Matsubara, S., Nagasono, M., Ohashi, H., Ohshima, T., Otake, Y., Shintake, T., Tamasaku, K., Tanaka, H., Tanaka, T., Togawa, K., Tomizawa, H., Watanabe, T., Yabashi, M., Ishikawa, T. 2011; 19 (1): 317–24

  Abstract

  The 13th harmonic of a Ti:sapphire (Ti:S) laser in the plateau region was injected as a seeding source to a 250-MeV free-electron-laser (FEL) amplifier. When the amplification conditions were fulfilled, strong enhancement of the radiation intensity by a factor of 650 was observed. The random and uncontrollable spikes, which appeared in the spectra of the Self-Amplified Spontaneous Emission (SASE) based FEL radiation without the seeding source, were found to be suppressed drastically to form to a narrow-band, single peak profile at 61.2 nm. The properties of the seeded FEL radiation were well reproduced by numerical simulations. We discuss the future precept of the seeded FEL scheme to the shorter wavelength region.

  View details for PubMedID 21263571

• Extreme ultraviolet free electron laser seeded by high-order harmonic Togashi, T., Takahashi, E. J., Midorikawa, K., Aoyama, M., Yamakawa, K., Sato, T., Iwasaki, A., Owada, S., Okino, T., Yamanouchi, K., Couprie, M. E., Hara, T., Kumagai, N., Matsubara, S., Nagasono, M., Ohshima, T., Otake, Y., Shintake, T., Tanaka, H., Tanaka, T., Togawa, K., Tomizawa, H., Watanabe, T., Yabashi, M., Ishikawa, T., IEEE IEEE. 2011

  View details for Web of Science ID 000295612402166

• Characterization of beryllium foils for coherent x-ray applications of synchrotron radiation and XFEL beamlines Goto, S., Takahashi, S., Inubushi, Y., Tono, K., Sato, T., Yabashi, M., Morawe, C., Khounsary, A. M., Goto, S. SPIE-INT SOC OPTICAL ENGINEERING. 2011

  View details for DOI 10.1117/12.894506

  View details for Web of Science ID 000297556300033

• Dissociative two-photon ionization of N-2 in extreme ultraviolet by intense self-amplified spontaneous emission free electron laser light APPLIED PHYSICS LETTERS Sato, T., Okino, T., Yamanouchi, K., Yagishita, A., Kannari, F., Yamakawa, K., Midorikawa, K., Nakano, H., Yabashi, M., Nagasono, M., Ishikawa, T. 2008; 92 (15)

  View details for DOI 10.1063/1.2911742

  View details for Web of Science ID 000255117100122