Toshio Horigome

Development of an X-ray pixel detector with multi-port charge-coupled device for X-ray free-electron laser experiments

This paper presents development of an X-ray pixel detector with a multi-port charge-coupled device (MPCCD) for X-ray Free-Electron laser experiments. The fabrication process of the CCD was selected based on the X-ray radiation hardness against the estimated annual dose of 1.6 × 10(14) photon/mm(2). The sensor device was optimized by maximizing the full well capacity as high as 5 Me- within 50 μm square pixels while keeping the single photon detection capability for X-ray photons higher than 6 keV and a readout speed of 60 frames/s. The system development also included a detector system for the MPCCD sensor. This paper summarizes the performance, calibration methods, and operation status.

In operando observation system for electrochemical reaction by soft X-ray absorption spectroscopy with potential modulation method

In order to investigate local structures of electrolytes in electrochemical reactions under the same scan rate as a typical value 100 mV/s in cyclic voltammetry (CV), we have developed an in operando observation system for electrochemical reactions by soft X-ray absorption spectroscopy (XAS) with a potential modulation method. XAS spectra of electrolytes are measured by using a transmission-type liquid flow cell with built-in electrodes. The electrode potential is swept with a scan rate of 100 mV/s at a fixed photon energy, and soft X-ray absorption coefficients at different potentials are measured at the same time. By repeating the potential modulation at each fixed photon energy, it is possible to measure XAS of electrochemical reaction at the same scan rate as in CV. We have demonstrated successful measurement of the Fe L-edge XAS spectra of aqueous iron sulfate solutions and of the change in valence of Fe ions at different potentials in the Fe redox reaction. The mechanism of these Fe redox processes is discussed by correlating the XAS results with those at different scan rates.

SAMRAI: A novel variably polarized angle-resolved photoemission beamline in the VUV region at UVSOR-II

A novel variably polarized angle-resolved photoemission spectroscopy beamline in the vacuum-ultraviolet (VUV) region has been installed at the UVSOR-II 750 MeV synchrotron light source. The beamline is equipped with a 3 m long APPLE-II type undulator with horizontally/vertically linear and right/left circular polarizations, a 10 m Wadsworth type monochromator covering a photon energy range of 6-43 eV, and a 200 mm radius hemispherical photoelectron analyzer with an electron lens of a +/-18 degrees acceptance angle. Due to the low emittance of the UVSOR-II storage ring, the light source is regarded as an entrance slit, and the undulator light is directly led to a grating by two plane mirrors in the monochromator while maintaining a balance between high-energy resolution and high photon flux. The energy resolving power (hnu/Deltahnu) and photon flux of the monochromator are typically 1 x 10(4) and 10(12) photons/s, respectively, with a 100 microm exit slit. The beamline is used for angle-resolved photoemission spectroscopy with an energy resolution of a few meV covering the UV-to-VUV energy range.

Construction of focusing soft x‐ray beamline BL1A at the UVSOR

A focusing soft x‐ray beam line equipped with a focusing premirror and a double crystal monochromator (DXM) has been constructed at BL1A in the UVSOR. An elliptically bent cylindrical mirror was used as the focusing premirror in order to attain both horizontal and vertical focusing at the sample position. Ray tracing shows that the size and shape of the focused spot at sample position with an elliptically bent cylindrical mirror is almost the same as that of an ellipsoidal mirror. Measured spot size of the monochromatic x‐ray beam at the sample position was about 2 mm wide and 1 mm high, which is in good agreement with the result of ray tracing. Monochromatic x rays were observed up to 4 keV even after reflection by a platinum coated premirror with grazing angle of 1°.

BL5U at UVSOR‐II for Three‐dimensional Angle‐resolved Photoemission Spectroscopy

BL5U at UVSOR‐II has been reconstructed in 2004’s for three‐dimensional angle‐resolved photoemission (3D‐ARPES) study on solids and surfaces. The beamline is equipped with a helically/linearly polarized undulator, an old‐type monochromator named as SGM‐TRAIN designed in 1995’s, and a new photoemission end‐station. Since their performances are insufficient to study anomalous electronic/magnetic properties on materials in recent years, we reconstructed the beamline for a high‐resolution study as follows; (1) The manipulation of the pre‐focusing mirror was updated to a high‐precision system controlled by pulse‐motors. (2) The entrance slit with water cooling system was adopted for avoiding the heat load from undulator radiation. (3) The SGM‐TRAIN was re‐arranged to the optimum condition to the undulator light. (4) The free tuning program of the undulator gap and monochromator‐control systems was introduced. Due to the reconstructions, we successfully improved the throughput intensity and energy resolution of...

Time-resolved synchrotron spectroscopy of exciton fluorescence in anthracene single crystals

Abstract Time-resolved fluorescence spectra have been investigated on anthracene crystals in the range of 4–12 eV by the time-correlated single-photon counting technique using pulsed radiation from a synchrotron source. The time-resolved excitation spectra of the singlet excitation fluorescence are significantly dependent on time and exciting photon energy. In a subnanosecond time period during the pulse excitation, the fluorescence detected near the absorption edge has a high quantum efficiency when the exciton bands are resonantly excited by the polarized light along the b -axis. Meanwhile, for the off-resonance excitations, the fluorescence rises with a time delay of about 1 ns and obeys a purely single-exponential decay. Possible interpretations of the time correlation between the flourescence and the excitation spectra observed in the subnanosecond time period are made on the basis of the excitonic polariton model.

Modification of a high vacuum, crossed molecular beam scattering system to perform angle-resolved, gas-surface scattering studies under ultrahigh vacuum conditions

A molecular beam apparatus which was formerly used for crossed molecular beam chemiluminescence experiments under high vacuum conditions has been modified into an ultrahigh vacuum apparatus with a rotatable mass spectrometer detector equipped with an electron bombardment ionizer to study (1) the molecule-surface scattering process, (2) molecular beam-surface reaction dynamics, and (3) light-excited molecular desorption. Every flange surface originally sealed using a Viton o ring is sealed with a combination of an inner spring-loaded Teflon or aluminum seal with an outer Viton o ring, the intermediate region being pumped with a diffusion pump. Due to the limited space available for a rotatable detector chamber and to make the neutral flight length in time-of-flight (TOF) measurements as long as possible, the electron bombardment ionizer is installed at the farthest end of a triply differentially pumped detector chamber; thus, the ions formed are extracted toward the reverse direction of the scattered neutr...

Construction and performance test of SGM-TRAIN at UVSOR

A new spherical-grating monochromator with translational and rotational assembly including a normal-incidence mount (SGM-TRAIN) has been constructed at BL5A of the UVSOR facility. The SGM-TRAIN is an advanced version of a constant-length SGM with the following improvements: (i) a wide energy range of 5-250 eV; (ii) a high resolving power; (iii) use of linear and circular polarization; (iv) reduction of second-order light; (v) two computer-controlled driving modes. Part of the performance tests are reported along with a detailed description of the design.

Development of in-situ sample cells for scanning transmission x-ray microscopy

An azimuthal rotatable sample cell, an electrochemical cell and a controlled humidity cell for in-situ scanning transmission X-ray microscopy (STXM) were developed at UVSOR-III Synchrotron (Okazaki, Japan). By using these sample cells, the polarization dependence of sodium titanate nanoribbons, in-situ electrochemistry of 0.1M FeSO4 solution, and in-situ morphological change of a functional polymer with changing humidity were successfully measured.

Time-Resolved Spectrophotometric System for Synchrotron Orbital Radiation

その接線方 向に放出され る電磁波 で あ る1).こ のSOR は従来の光源 にはなか ったい くつか の優れた特徴を もっ ている ことか ら,分 光学実験 の光源 として,ま た リソグ ラフ ィーな どの応用研究 の光源 として有用で あ り,す で に先駆的 な研究 が行われ ている,国 内にお いてはい くつ かの研究機 関において,電 子線発生装置お よび電子加速 ス トレージ リングが運転稼働 中で あ り,ま た新た な建設 計画 が進 め られ ている2). 最近,実 用運転 には いった分子科学研究所,極 端紫外 光実験施設 のス トレージ リング(通 称UVSOR)は,加 速 エネルギー600MeV(最 大750MeV)で 貯蔵 電 流 100mA(最 大500mA)の 中型 の リングで ある.こ の リ ングか ら得 られ るSORは,有 効波 長範 囲が10Aか ら 赤外線に至 る 極め て 広い領域で 連続 した 分光分布を示 し,そ の電気ベ ク トルは リングの軌道面に平行な直線偏 光特性を もってい る.通 常の運転ではマルチバ ンチ運転 が行われ,周 長50mの リングを16個 の電子バ ンチが 周 回してい る(マ ルチバ ンチ と称す る).こ れに よって SORは パルス間隔11ns,1個 のパル スの半値幅はお よ