中西 康次

A bacterial siliceous iron oxide microtubule (diameter: ca. 1 mu m, 15Fe(2)O(3)center dot 8SiO(2)center dot P2O6 center dot 30H(2)O) produced by Leptothrbc ochracea was heat treated in air and its structural transformation was investigated in detail by microscopy, diffractometry, and spectroscopy. Although the heat-treated bacterial iron oxide retained its original microtubular structure, its nanoscopic, middle-range, and local structures changed drastically. Upon heat treatment, nanosized pores were formed and their size changed depending on temperature. The Fe O Si linkages were gradually cleaved with increasing temperature, causing the progressive separation of Fe and Si ions into iron oxide and amorphous silicate phases, respectively. Concomitantly, global connectivity and local structure of FeO6 octahedra in the iron oxide nanoparticles systematically changed depending on temperature. These comprehensive investigations clearly revealed various structural changes of the bacterial iron oxide which is an important guideline for the future exploration of novel bio-inspired materials. (C) 2015 Elsevier B.V. All rights reserved.

Surface modification of a layered polysilane consisting of two-dimensional crystalline silicon layers was investigated using n-alkylamines, alpha,omega-diaminoalkanes, and ?-aminocarboxylic acids. All products of the reactions with n-butyl- to n-hexadecylamines were dispersed as nanosheets in chloroform and exhibited the same blue light emission and photoluminescence spectra when exposed to UV light. After removal of the solvent, these products formed regularly stacked structures with an interlayer distance that increased in proportion to the alkyl length. The structure consists of bilayered alkyl chains with a tilt angle of ca. 47 degrees. When the layered polysilane was reacted with alpha,omega-diaminoalkanes, the products were not dispersed in chloroform, because the silicon layers were covalently bonded by the diamines. The interlayer distances for these products also increased in proportion to the alkyl length. The layered polysilane was also successfully reacted with 12-aminododecanoic acid in pyridine or other polar solvents, where the formation of Si-N bonds was confirmed by Si K-edge X-ray absorption near-edge structure analysis. This result indicates that a highly reactive carboxyl group can be introduced onto the silicon layer surface. A chloroform solution of the 12-aminododecanoic acid-modified polysilane exhibited the same blue light emission as the polysilane modified with n-alkylamines.

© 2015 The Electrochemical Society. All rights reserved. Li<inf>2</inf>S-FeS<inf>x</inf> (x = 1, 2) composite positive electrode material, consisted of low-crystalline Li<inf>2</inf>S, was prepared by the combination process of the thermal heating and the mechanical milling. The electrochemical tests demonstrated that the Li<inf>2</inf>S-rich composite sample (Li<inf>2</inf>S : FeS = 4 : 1 mol) cells showed relatively high initial charge capacity (ca. 600 mAh · g<sup>-1</sup>). The discharge capacity was ca. 330 mAh · g<sup>-1</sup> with the normal electrochemical cycling, and it was enlarged to ca. 730 mAh · g<sup>-1</sup> after the stepwise pre-cycling treatment. Ex situ XRD measurements showed the improved reversibility of the Li<inf>2</inf>S peaks for Li extraction/insertion reactions after the stepwise pre-cycling treatment. Also, ex situ S and Fe K-edge XAFS measurements indicated the improved reversibility of the valence states and local structures around S and Fe atoms after the stepwise pre-cycling treatment. Thus, the stepwise precycling treatment was effective for improving the structural reversibility of the Li<inf>2</inf>S-FeS<inf>x</inf> composites, particularly with Li<inf>2</inf>S-rich composition, for Li insertion/extraction reactions, resulting in the improved electrochemical performances of the cells.

To elucidate the Li+ extraction and insertion mechanism for Li2FeSiO4 nanoparticles, at the atomic scale, X-ray absorption spectroscopy (XAS) measurements at Fe and Si K-edges were performed. Fe K-edge XAS spectra suggest irreversible changes occurring in the local and electronic environment of iron which can be attributable to the characteristic shift in potential plateau during initial cycling of Li2 - xFeSiO4 system. While the local environment around Fe atoms significantly changes upon initial cycling, the local Si-O environment is mostly maintained. (C) 2013 Elsevier B.V. All rights reserved.

Graphite-solid electrolyte (SE) composite anode, prepared by spark-plasma-sintering (SPS) process, was applied to all-solid-state lithium secondary batteries with lithium sulfide (Li2S) positive electrode. The electrochemical tests demonstrated that the graphite-SE/Li2S cells showed the discharge capacity of ca. 750 mAh.g(-1)-Li2S with the average voltage of ca. 1.98 V. Although the discharge capacity was lower than that of the In/Li2S cells (ca. 920 mAh.g(-1)-Li2S), the estimated energy density was higher than that (ca. 1490 and 1220 mWh.g(-1)-Li2S for graphite-SE/Li2S and In/Li2S cells, respectively), due mainly to its higher average voltage. The graphite-SE/Li2S cells showed improved rate capability as compared with the cells with the graphite + SE blended powder, which was attributable mainly to the reduced interfacial resistance between the graphite and SE particles caused by the SPS process. (C) 2013 Elsevier B.V. All rights reserved.

A novel spectro-electochemical cell for X-ray absorption spectroscopy in the tender X-ray region (TX-XAS) was designed and fabricated to investigate the electrochemical behavior of common battery materials with liquid electrolytes under in situ/operando conditions. The cell has several unique features, such as high X-ray transmittance, high signal to noise ratio, and high vacuum tightness. These features enable us quick and reliable XAS measurements. Operando P K-edge XAS measurements of an olivine-type LiFePO4 composite positive electrode were carried out to clarify its phosphorus environment during the electrochemical charging process. Results of spectral analysis show that there is no significant change in the oxidation state of phosphorus and in the coordination of the phosphate anions in the charging process, but a closer look of the consecutive XAS spectra suggests the shrinkage of the PO4 cage during the charging process, and the structural changes in a biphasic manner. These results demonstrate the usefulness of the cell for in situ/operando TX-XAS observations of light elements in practical batteries. (C) 2014 AIP Publishing LLC.

For the further development of lithium-ion batteries, improvement of their cyclic performance is crucial. However, the mechanism underlying the deterioration of the battery cyclic performance is not fully understood. We investigated the effects of the electronic structure at the electrode/electrolyte interface on the cyclic performance of the cathode materials via in situ total-reflection fluorescence X-ray absorption spectroscopy. In a LiCoO2 thin-film electrode that exhibits gradual deterioration upon subsequent Li ion extractions and insertions (cycling), the reduction of Co ions at the electrode/electrolyte interface was observed upon immersion in an organic electrolyte, with subsequent irreversible changes after cycling. In contrast, in a LiFePO4 thin-film electrode, the electronic structure at the electrode/electrolyte interface was stable and reversible upon electrolyte immersion with subsequent cycling. The increased stability of the electronic structure at the LiFePO4/electrolyte interface affects its cycling performance.

70Li2S · 30P2S5(mol%) solid electrolytes (SE) were prepared with much shorter time (within several hours) by applying higher mechanical stress using a pulverizer. The obtained SE (MM sample) showed rather development of the crystalline Li7P3S11as compared with the glass SE, resulting in the conductivity value between the crystalline and glass SE. By applying to the graphite/Li2S all-solid-state cells, improved energy density, as compared with that of the In/Li2S cells, was achieved. The rate capability of the graphite/Li2S cells was dependent on the conductivity of the SE. The present milling process using a pulverizer is advantageous for producing the SE being applicable for all-solid-state battery production. © 2014 The Electrochemical Society.

Li2S-FeS2composite positive electrode materials were prepared for improving the discharge capacity of the allsolid-state In/Li2S cells via the electrical conductivity enhancement of Li2S. The electrochemical tests demonstrated that the In/Li2S-FeS2(Li2S: FeS2= 3:7 wt) cells showed relatively higher discharge capacity (ca. 180 mAh • g-1, normalized by the cathode weight) than that of the In/Li2S-C cells (ca. 140 mAh •g-1), due to the increased fraction of the active materials in the cathodes. The ex-situ XRD and S K-edge XAFS results indicated that the In/Li2S-FeS2cells showed similar electrochemical reaction to that of the Li/Li2S-FeS2cells with liquid electrolytes during charge, but did not proceed to form Li2S and Fe during discharge. Such difference was due to the limited amounts of Li ions supplied from the lithiated-In anode during discharge for the In/Li2S-FeS2cells.

We prepared a Cu2ZnSn(SxSe1-x)(4) (CZTSSe) solid solution from elemental powders. The CZTSSe solid solutions were synthesized by heating the elemental mixtures at 550 degrees C for 5 h in an N-2 gas. All CZTSSe materials were analyzed by Rietveld analysis using the kesterite structure with a space group of I (4) over bar (No. 82). Rietveld analysis showed that the lattice parameters, a and c, monotonically decreased with increasing S content. Moreover, the local structures of the Cu and S atoms were investigated by X-ray absorption near edge structure (XANES). Although the local structure of the S atom in CZTSSe hardly changed in relation to the S/Se ratio, we found that the surface of CZTSSe powders became slightly oxidized. On the other hand, Cu K edge XANES showed that the S/Se ratio could be easily determined from the XANES spectra. The band gap energies of the CZTSSe materials were determined by transmittance and diffuse-reflectance spectra. The transmittance spectra were recorded using CZTSSe films fabricated by a printing and high-pressure sintering (PHS) process. The band gap energy, E-g, monotonically increased from 1.05 eV for CZTSe to 1.51 eV for CZTS. (C) 2012 The Japan Society of Applied Physics

We investigated the chemical bonding states at the ZnO/CdS interface by X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS) measurements. We found that the octahedral ZnO6 species formed in the initial stage of the ZnO deposition from the Zn L-3-edge X-ray absorption near-edge structure spectra. On the other hand, it is difficult to discuss the change of the chemical bonding states of the Zn atoms through the Zn 2p(3/2) and the S 2p photoelectron spectra. In addition, we suggested that CdSO4 formed at the ZnO/CdS interface from the analysis of the O 1s photoelectron spectra. We enabled the significant investigation of the chemical bonding states at the ZnO/CdS interface by using a combination of XPS and XAFS measurements. Crown Copyright (c) 2012 Published by Elsevier B.V. All rights reserved.

Transfer of a CuInS2 thin film grown on a Mo/soda-lime glass substrate was investigated using a lift-off process. The CuInS2 thin film was flatly exfoliated, with preferential peeling occurring in the CuInS2/MoS2 interface vicinity. This suggests that the interfacial MoS2 layer behaves as a sacrificial layer. The lift-off process was also applied to solar cell fabrication. A superstrate-type CuInS2 thin-film solar cell was fabricated and exhibited no significant degradation of conversion efficiency compared with a substrate-type CuInS2 thin-film solar cell. The lift-off process could therefore also be applied to fabricate the upper part of a tandem solar cell structure. (C) 2012 Elsevier B.V. All rights reserved.

Alkyl-modified crystalline silicon nanosheets 2 were synthesized and maintained the crystal structure of a Si(111) plane, in which the dangling silicon bond is stabilized by capping with the alkyl group. 2 was characterized using UV-vis, Fourier transform-infrared, and X-ray photoelectron spectroscopies; X-ray diffraction; and X-ray absorption near edge structure analysis. A model structure is proposed that has a periodicity through the nanosheet surface. © 2012 American Chemical Society.

The cobalt and cobalt nitride nanoparticles (NPs) have been fabricated by gas evaporation method under helium or nitrogen gases environment. These chemical states and compositions have been investigated by in-situ XPS and those distributions have been estimated by AFM. It is found that both cobalt and cobalt nitride NPs are slightly oxidized by the residual gas in the chamber. The cobalt nitride NPs fabricated under nitrogen gas are including the nitrogen atoms at 4.7% and the nitrogen atoms have the chemical bonding with the cobalt atoms.

FeS -Li S composite positive electrode material, consisted of mainly Li Fe S and Li Fe S , was prepared for improving the cycle capability of FeS in rechargeable lithium batteries with liquid electrolytes operated at ambient temperature. The electrochemical tests demonstrated that the FeS -Li S composite cells showed a relatively higher capacity retention after 15 cycles (ca. 64%) as compared with that of the FeS cells (ca. 26%), though both sample cells showed comparable initial discharge capacities (ca. 740 and 790 mAh·g (4.2 and 4.5 mAh·cm ), respectively). The improved cycle capability of the FeS -Li S cells was ascribed particularly to rather unchanged discharge plateau at ca. 2.0 V, which was reported to correspond to the reduction of sulfur. The ex-situ S K-edge X-ray absorption fine structure measurements indicated that the redox reaction of sulfur ions (S + 2e 2S ), associated with Li extraction / insertion reactions, was still active after 15 cycles in the FeS -Li S electrode, while such redox reactions almost disappeared in the FeS electrode. The atomic displacements required in the initial delithiation / lithiation were reduced in the FeS -Li S composite as compared with FeS , which would give rise to the suppression of the structural irreversibility in the following charge / discharge, resulting in the improved cycle capability. © 2011 The Electrochemical Society. 2 2 3 2 4 2.33 0.67 2 2 2 2 2 2 2 2 2 2 2 2 2 2 -1 -2 2- - 2-

In an attempt to identify an active material for use in lithium secondary batteries with high energy density, we investigated the electrochemical properties of gallium (III) sulfide (Ga S ) at 30 °C. Ga S shows two sloping plateaus in the potential range between 0.01 V and 2.0 V vs. (Li/Li ). The specific capacity of the Ga S electrode in the first delithiation is ca. 920 mAh g , which corresponds to 81% of the theoretical capacity (assuming a 10-electron reaction). The capacity in the 10th cycle is 63% of the initial capacity. Ex situ X-ray diffraction and X-ray absorption fine structure analyses revealed that the reaction of the Ga S electrode proceeds in two steps: Ga S + 6Li + 6e 2Ga + 3Li S and Ga + xLi + xe Li Ga. © 2011 Elsevier B.V. All rights reserved. 2 3 2 3 2 3 2 3 2 3 2 x + -1 + - + -

We have been developing a cryogenic system for biospecimens at soft X-ray microscope with a compact SR source. We present here the features of this system and the results obtained for some biospecimens. The microscope used can image specimens surrounded by cold nitrogen gas from liquid nitrogen under atmospheric pressure. The liquid nitrogen flux is controlled by a temperature controller with a platinum resistance thermometer. The specimens can be maintained at the temperature preset within the range of 110-273 K. The cryogenic system has been installed at the X-ray microscopy beamline and the first cryogenic images have been acquired. (C) 2011 The Japan Society of Applied Physics

For analysis of lithium ion batteries, the soft X-ray grating monochromator beamline BL-2 at SR center of Ritsumeikan University has been upgraded: adding a new grating (900 l/mm) to extend the available energy up to 1000 eV, and constructing a XAFS (X-ray Absorption Fine Structure)-PES (photoelectron spectroscopy) chamber equipped with in-situ transfer vessel systems. With this beamline, Li K-, O K- and 3d transition metal (TM) L- XAFS and Li 1 s PES spectra were measured for several compounds related to Li ion batteries. For precise analysis of the Li chemical state, some of Li compounds, as well as Li metal were prepared by vacuum deposition.

The synthesis of silicon nanosheets for fabricating electronic devices, without using conventional vacuum processes and vapor deposition, is challenging and is anticipated to receive significant attention for a wide range of applications. Here, we report the synthesis of oxygen-free, phenyl-modified organosilicon nanosheets with atomic thickness. In organic solvents, a consequence of this new silicon structure is its uniform dispersion and the possibility of exfoliation into unilamellar nanosheets. Light-induced photocurrent in [Si(6)H(4)Ph(2)] was observed, leading to the possibility of various organosilicon nonamaterials with useful properties.

Silicon nanomaterials are encouraging candidates for application to photonic, electronic, or biosensing devices, due to their size-quantization effects. Two-dimensional silicon nanosheets could help to realize a widespread quantum field, because of their nanoscale thickness and microscale area. However, there has been no example of a successful synthesis of two-dimensional silicon nanomaterials with large lateral size and oxygen-free surfaces. Here we report that oxygen-free silicon nanosheets covered with organic groups can be obtained by exfoliation of layered polysilane as a result of reaction with n-decylamine and dissolution in an organic solvent. The amine residues are covalently bound to the Si(111) planes. It is estimated that there is ca. 0.7 mol of residue per mole of Si atoms in the reaction product. The amine-modified layered polysilane can dissolve in chloroform and exfoliate into nanosheets that are 1-2 microm wide in the lateral direction and with thicknesses on the order of nanometers. The nanosheets have very flat and smooth surfaces due to dense coverage of n-decylamine, and they are easily self-assembled in a concentrated state to form a regularly stacked structure. The nanosheets could be useful as building blocks to create various composite materials.

We have developed a compact experimental set-up for X-ray absorption fine structure (XAFS) measurements in He at atmospheric pressure (AP) in the soft X-ray region and used it for Mg and Cl K-edge XAFS measurements of MgCl2 and MgCl2 center dot 6H(2)O. The spectra of MgCl2 center dot 6H(2)O measured in He at AP were significantly different from those measured in vacuum. This suggests the importance of performing soil X-ray XAFS experiments under AP to obtain reliable spectra from hydrated compounds.

In our effect to develop a lithium secondary battery with high energy density, aluminum sulfide (Al S ) was studied for use as an active material. The measured initial discharge capacity of Al S was ca. 1170 mAh g at 100 mA g . This corresponds to 62% of the theoretical capacity for the sulfide. Al S exhibited poor capacity retention in the potential range between 0.01 V and 2.0 V, mainly due to the structural irreversibility of the charge process or Li extraction. XRD and Al and S K-XANES analyses indicated that the surface of Al S reacts reversibly during charge and discharge processes, while the core of Al S showed structural irreversibility because LiAl and Li S were formed from Al S at the initial discharge and remained as they were afterward. © 2010 Elsevier B.V. All rights reserved. 2 3 2 3 2 3 2 3 2 3 2 2 3 -1 -1

Electrochemically active lithium sulfide-carbon (Li S-C) composite positive electrodes, prepared by the spark plasma sintering process, were applied to all-solid-state lithium secondary batteries with a PO - Li S- SiS glass electrolyte. The electrochemical tests demonstrated that In/ Li S-C cells showed the initial charge and discharge capacities of ca. 1010 and 920 mAh g-1 - Li S, respectively, which showed higher discharge capacity and coulombic efficiency (ca. 91%) than the Li/ Li S-C cells with nonaqueous liquid electrolytes (ca. 200-380 mAh g - Li S and ca. 27%, respectively). The ex situ S K-edge X-ray absorption fine structure measurements suggested the appearance and disappearance of elemental sulfur in the positive electrodes after charging and discharging, respectively, indicating that the ideal electrochemical reaction Li S 2Li+S proceeded in the present all-solid-state cells. Such ideal electrochemical reaction, due probably to the suppression of the dissolution of Li S in the form of polysulfides into the electrolytes, would result in higher coulombic efficiency and discharge capacity as compared with those of the liquid-electrolyte cells. © 2010 The Electrochemical Society. 2 Li3 4 2 2 2 2 2 2 2 2 -1

Electrochemically active lithium sulfide-carbon (Li2S-C) composite positive electrodes, prepared by the spark plasma sintering process, were applied to all-solid-state lithium secondary batteries with a Li3PO4-Li2S-SiS2 glass electrolyte. The electrochemical tests demonstrated that In/Li2S-C cells showed the initial charge and discharge capacities of ca. 1010 and 920 mAh g(-1)-Li2S, respectively, which showed higher discharge capacity and coulombic efficiency (ca. 91%) than the Li/Li2S-C cells with nonaqueous liquid electrolytes (ca. 200-380 mAh g(-1)-Li2S and ca. 27%, respectively). The ex situ S K-edge X-ray absorption fine structure measurements suggested the appearance and disappearance of elemental sulfur in the positive electrodes after charging and discharging, respectively, indicating that the ideal electrochemical reaction Li2S double left right arrow 2Li + S proceeded in the present all-solid-state cells. Such ideal electrochemical reaction, due probably to the suppression of the dissolution of Li2S in the form of polysulfides into the electrolytes, would result in higher coulombic efficiency and discharge capacity as compared with those of the liquid-electrolyte cells. (C) 2010 The Electrochemical Society. [DOI:10.1149/1.3486083] All rights reserved.

We deposited 0.01-0.16 ML (monolayer) of potassium on stepped (7 5 5) [=6(1 1 1) x (1 0 0)] surface of nickel in order to fabricate and to understand the growth process of one-dimensional (1D) potassium atomic-chain structure by observing the low-energy-electron-diffraction (LEED) patterns. The LEED patterns from potassium adsorbates exhibit a distinct coverage dependence that 1 x streaks first appeared at low coverages up to 0.04 ML and later 2 x streaks appeared at around 0.09 ML. The streaks become spotty at the higher coverage. We explained these coverage-dependent changes in LEED patterns in a thorough comparison with kinematically calculated LEED patterns constructing a reasonable growth model. (C) 2008 Elsevier B.V. All rights reserved.

We have improved a display-type spherical mirror analyzer (DIANA) at Ritsumeikan University SR Center BL-7 for in situ real space mapping of electronic and atomic structures that uses a focused electron beam and a linearly polarized synchrotron radiation (SR). The outer sphere was fully optimized. Compared to the previous analyzer, the energy resolution (Delta E/E) has been improved from 1% to 0.09 +/- 0.02%. A newly designed electron gun for measurement of atomic structures was installed inside the analyzer. Thus the measurement of electronic and atomic structures at the same sample position became possible. Here we report on the improvements of the new DIANA and the results of the first in situ measurement of real space mapping of the valence band and scanning Auger electron microscopy (SAM) of a multiple domain Kish graphite. The crystal orientations of each domain were determined from the electronic structures. (C) 2008 Elsevier B.V. All rights reserved.

The local structure around Si species in mesoporous silica FSM-16 was investigated by Si K-edge XAFS. As expected from the previous studies, the local symmetry of Si species in FSM-16 is almost identical to that of amorphous silica. The Si-O bond length was longer than those of alpha-quartz, ZSM-5, and amorphous silica. Relations between the prolonged bond length and the acidic property of FSM-16 were discussed.

A novel hydrogen permeable membrane was prepared from zeolite Na-A crystals, dissolved in a HCl solution and spin-coated on a Vycor glass plate, The membrane shows high-separation factors for H-2/CH4 (> 1200), H-2/N-2 (> 1600) and H-2/CO (>660) binary gas mixtures at 298 K. Such a highly selective H-2 permeation suggests that the membrane composed of zeolite nano-blocks possesses no 8-membered oxygen rings as permeable pores. The membrane is characterized by X-ray diffraction, Al-27, Si-29 NMR and Al, Si K-edge X-ray absorption near edge structure spectroscopy. A dealuminization from the zeolite framework occurs during the dissolution in acid solutions, but the zeolite nano-blocks still keep the local structure of zeolite although CO-permeable 8-membered oxygen rings disappear. Alumina-like nanoparticles formed by the dealuminization must be embedded in the aggregate of zeolite nano-blocks. (c) 2007 Elsevier B.V. All rights reserved.

We have reconstructed a vacuum ultraviolet beamline BL-7 for solid state and surface science covering a photon energy range of 10-160 eV A set of four spherical grating are used, which are designed to cover the energy range of 10-20 eV, 20-40 cV, 40-80 eV, and 80-160 eV, respectively. The lower limit of the photon energy was extended for the investigation of surface electronic structures which typically have a photoexcitation cross section maxima at 10-20 eV The higher limit was extended for the access of many important core levels such as 2p of Si and 3s/3d of transition metals. The photon flux was evaluated by the photocurrent measurement. The energy range were greatly extended compared to that of the previous one. The spot size of the zeroth-order light at the sample surface was 1.25 nun (horizontal) x 0.32 mm (vertical). Furthermore, a newly designed display-type spherical mirror analyzer was installed at the end station.

We have investigated the surface electronic structure of stepped Ni(332)[=6(111)x(111)] in the expectation of observing one-dimensional surface state by angle-resolved ultraviolet photoelectron spectroscopy using synchrotron radiation(SR-ARUPS). In SR-ARUPS spectra, we observed two surface-sensitive peaks at -0.5 and -0.1 eV below Fermi level E-F revealed by O-2 adsorption. The former peak disperses downwards away from EF parallel and perpendicular to the steps, which can be attributed to the (111) terrace-derived two-dimensional surface state. Though the latter peak disperses upwards parallel to the steps, on the other hand, it has almost no dispersion in the perpendicular direction. This flat dispersion is the clear evidence that the peak just below EF stems from an electronic state localized at the steps. Considering the flat and upwards dispersions perpendicular and parallel to the steps, this step-localized state is concluded to be one-dimensional electronic state.

We have developed and installed a new DIsplay-type ANAlyzer (DIANA) at Ritsumeikan SR center BL-7. We measured the angle-integrated energy distribution curve of poly-crystal gold and the photoelectron intensity angular distribution (PIAD) of HOPG to estimate the total energy resolution and to check the condition of the analyzer. The total energy resolution (Delta E/E) is up to 0.78%, which is much higher than the old type. The PIAD of HOPG we obtained was the ring pattern as expected. Therefore, a detailed three-dimensional Fermi surface mapping and an analysis of the atomic orbitals constituting the electron energy bands are possible by combining them with a linearly polarized synchrotron radiation.

We deposited a submonolayer of potassium on stepped (755)[=6(111)x(100)] surfaces of copper and nickel in order to fabricate one-dimensional (1D) atomic-chain structures. Upon deposition of 0.09-ML potassium, we obtained 1D atomic chains on Ni(755) but not on Cu(755) as revealed from the low-energy-electron-diffraction(LEED) patterns. The difference in potassium structure has been attributed to the difference in interaction of potassium adsorbates with terraces and steps of the substrates.

A method for atomic-orbital orientation determination at each k point has been developed. The three-dimensional Cu Fermi surface (FS) structure was measured and visualized by stacking a series of photoelectron intensity angular distribution (PIAD) at different photon energies. PIADs from the Cu(001) surface were obtained using a display-type analyzer and linearly polarized synchrotron radiation. The atomic orbitals composing the FS were determined to be mainly 4p orbitals with their axes pointing outward. Atomic orbital orientations at different k coordinates on FS as well as the FS cross-section structures were revealed directly from experiment and were confirmed by ab initio calculation. © 2005 The American Physical Society.