e-Journal of Surface Science and Nanotechnology
Online ISSN : 1348-0391
ISSN-L : 1348-0391
Current issue
Showing 1-35 articles out of 35 articles from the selected issue
Regular Papers
  • Masaki Yamanashi, Kouichi Tsuji
    Type: Regular Paper
    Subject area: Instrumentations and Techniques
    2020 Volume 18 Pages 1-7
    Published: January 30, 2020
    Released: January 30, 2020
    JOURNALS OPEN ACCESS

    We developed a full-field X-ray diffraction (FFXRD) imaging method using a straight polycapillary realized in the laboratory that can obtain X-ray diffraction (XRD) images with a large area in a short time throughout the simple process without the synchrotron radiation facility. The FFXRD imaging instrument can obtain the XRD images of several millimeter sizes in several hundreds of seconds at each lattice plane. The positional resolution and the spatial resolution was improved by using a straight polycapillary with long type. The FFXRD imaging instrument was attached to the heat treatment system and Cu plate was heat-treated at 300°C. As an example of in situ monitoring of the change in the crystal structure distribution, a high-temperature oxidation process of Cu was observed. The XRD images of Cu, Cu2O, and CuO at each lattice plane were obtained every hour. While the crystal structure distribution of Cu was reduced, the crystal structure distribution of Cu2O and CuO were increased with the oxidation process of Cu by the heat treatment. The change of the crystal structure distribution near the surface by the oxidation process of Cu was confirmed. The XRD image obtained by the FFXRD imaging instrument was analyzed by micro-XRD measurements and confirmed that the FFXRD imaging instrument can accurately obtain the crystal structure distribution. In order to obtain the XRD image with a large area, the FFXRD imaging instrument that can be realized in the laboratory has advantages regarding the exposure time of X-rays and in situ analysis.

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  • Toshiyuki Yoshida, Islam Md Maruful, Yasuhisa Fujita
    Type: Regular Paper
    Subject area: Nano-Materials
    2020 Volume 18 Pages 12-17
    Published: February 06, 2020
    Released: February 06, 2020
    JOURNALS OPEN ACCESS

    Direct Ga-doping into ZnO nanoparticles (NPs) were tried by thermal treatment mixed with Ga2O3 particles. Residual Ga2O3 particles were completely removed by appropriate centrifugation process. To confirm the Ga-doping, variations of sheet resistances for sprayed NP-layers on glass substrates were investigated, showing successful and dramatic reduction from GΩ sq−1-order to sub-kΩ sq−1. The minimum sheet resistance reached to 225 Ωsq−1. From X-ray diffraction and X-ray photoelectron spectroscopy analyses, it can be concluded that Ga atoms diffused from Ga2O3 into ZnO-NPs in the thermal treatment process, and some of them substituted for Zn atoms and were activated as donors. These results can contribute to continuous advance of ZnO-NP-based thin-film-transistor fabrication technique.

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  • Mitsunori Kitta, Hiroshi Onishi
    Type: Regular Paper
    Subject area: Crystal Growth
    2020 Volume 18 Pages 32-37
    Published: February 22, 2020
    Released: February 22, 2020
    JOURNALS OPEN ACCESS
    Supplementary material

    Orthorhombic-type sodium tantalite (NaTaO3) is one of the most promising photocatalyst for hydrogen generation via water splitting reaction with ultraviolet-irradiation. In this research, we prepared NaTaO3 crystal from KTaO3 substrate via solid-state K+−Na+ alkaline cation substitution. In the transmission electron microscopy (TEM) observation revealed the perovskite-type KTaO3 crystal phase is transformed into the orthorhombic crystal phase via simple heating of KTaO3 substrate with Na2O2. Atomic scale scanning TEM imaging with energy dispersive X-ray spectroscopy (EDS) are supported that this phase transformation clearly based on the topotactic alkaline cation substitution with K+ and Na+ at a common Ta-O basic lattice structure.

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  • Andrey Menshakov, Seif Cholakh
    Type: Regular Paper
    Subject area: Thin Films
    2020 Volume 18 Pages 38-40
    Published: February 29, 2020
    Released: February 29, 2020
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    The article describes a new method of organosilicon compounds activation by low energy electron beam for SiCN coatings deposition. The composition of the beam plasma in a hexamethyldisilazane-containing gas medium was studied, and it was shown that the precursor molecules decomposition degree increases with the beam current and nonmonotonically depends on the electron beam energy. The application of a low-energy electron beam for the plasma-chemical vapor decomposition of hexamethyldisilazane and for samples heating up by electron beam to 600°C makes it possible to obtain SiCN-based coatings with a hardness up to 18 GPa and thickness ∼1 μm for 1 h.

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  • Ova Kurniawan, Bambang Soegijono
    Type: Regular Paper
    Subject area: Interdisciplinary
    2020 Volume 18 Pages 62-69
    Published: March 05, 2020
    Released: March 05, 2020
    JOURNALS OPEN ACCESS

    Electrical transmission overhead lines use an aluminum conductor in services. However, protection of the aluminum conductor from corrosion has to be considered. Hence, an extensive experimental work was done to prepare the composite coating of the aluminum conductor. Three types of polyurethane composites were fabricated with different fillers (5 wt% carbon and 5 wt% organoclay) and were characterized. The composites were polyurethane/carbon (PC), polyurethane/organoclay (PClay), and polyurethane/carbon/organoclay (PCClay). Thermogravimetry analysis and Fourier transform infrared spectroscopy were conducted to obtain thermal properties and chemical bonding of the composites. To obtain the corrosion resistance, salt spray tests were applied. To obtain hydrophobicity properties, the contact angle between water and the composites was measured. Measurements of composites relative permittivity was conducted to obtain dielectric properties. A water vapor permeability test was conducted to obtain the rate of water/gas vapor discharge. Finally, an adhesion test was conducted to obtain adhesion performance according to the ASTM D3359 standard. Based on characterization, PCClay had better characters to be used as an overhead aluminum coating material followed by PC and PClay.

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  • Rui Niu, Qing Yang, Xucheng Zhang
    Type: Regular Paper
    Subject area: Catalysis
    2020 Volume 18 Pages 76-80
    Published: March 14, 2020
    Released: March 14, 2020
    JOURNALS OPEN ACCESS

    Porous ZnO micron powders are obtained by thermal oxidation in air. The as-obtained powders are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen adsorption, and ultraviolet-visible spectrophotometer, and the photocatalytic degradation of methyl orange (MO) is evaluated. The results indicate that, with the increase in thermal oxidation temperature, the nanoparticles on the surface of porous ZnO gradually grow and connect to each other, and the porous structure is destroyed, which results in the decrease in the specific surface area. Porous ZnO obtained at 800°C exhibits the best photocatalytic performance for MO degradation. The highest degradation rate is 0.043 min−1 using 10 mg of the ZnO powders and 10 mg L−1 of the MO solution.

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  • Sunwei Chen, Ryo Murakami, Koya Araki, Masanori Owari
    Type: Regular Paper
    Subject area: Nano-Science and -Technology
    2020 Volume 18 Pages 127-132
    Published: April 09, 2020
    Released: April 09, 2020
    JOURNALS OPEN ACCESS

    The paper reports results of a systematic investigation of electric field effects on residual H signals in atom probe analysis. Three species, H+, H2+, and H3+, can be detected on a Pt surface without gas introduction into the ultra-high vacuum chamber. The H+ ions are more likely to be detected at a higher electric field. On the other hand, the H2+ and H3+ ions appear at the lower electric field. A comparison of residual H and a D2 gas confirmed that residual H is in the H2 gas form. H2 can be dissociated to H on the Pt surface. Consequently, H, H2, and H3 coexist on the Pt surface and desorb at an appropriate electric field.

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  • Kazuo Soda, Shinya Sugiura, Kanta Yamaguchi, Masahiko Kato, Ken Niwa, ...
    Type: Regular Paper
    Subject area: Nano-Science and -Technology
    2020 Volume 18 Pages 152-158
    Published: April 23, 2020
    Released: April 23, 2020
    JOURNALS OPEN ACCESS

    The hydrogen content x of Nb hydrides, NbHx and/or NbDx, formed in supercritical water under extremely high pressures and temperatures were studied as a function of the depth from the hydride surface via ion-beam analyses (elastic recoil detection analysis with Rutherford backscattering spectrometry, ERDA/RBS). The hydrogen-rich α'-NbH (x ≈ 0.9) formed a surface layer approximately 200-nm thick with a 4−25 nm Nb oxide overlayer, which was invisible or only barely visible in the X-ray diffraction (XRD) analysis, whereas the hydrogen-poor α-NbH (x < 0.2) was visible to a depth of 1 μm in the bulk. The oxide overlayer thickened with further hydrogenation. The exchange of D with H was suggested in the surface region for the hydride specimen formed with D2O. The chemical states of the studied specimens were also analyzed via the angle-dependent hard X-ray photoelectron spectroscopy, HAXPES. The formation mechanism of Nb hydrides is discussed based on the depth profiles of the hydrogen content x and the chemical states, as well as XRD results of the Nb hydrides.

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  • Karimov Mukhtorjon Karimberganovich, Kutliev Uchkun Otoboyevich, Ismai ...
    Type: Regular Paper
    Subject area: Thin Films
    2020 Volume 18 Pages 164-167
    Published: April 23, 2020
    Released: April 23, 2020
    JOURNALS OPEN ACCESS

    The energy and angular distributions of particles scattered Ar+ ions on the surface of InGaP(001)<110> have been calculated. The correlation between experimental and calculated angular distributions of the scattered particles has been presented. It has been shown that the semichanneled ions formed the characteristic peaks in the energy distributions of the scattered particles.

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  • Masakazu Ichikawa
    Type: Regular Paper
    Subject area: Nano-Materials
    2020 Volume 18 Pages 190-200
    Published: May 21, 2020
    Released: May 21, 2020
    JOURNALS OPEN ACCESS

    Equations on excitation and light emission of the localized bulk and surface plasmons for metal nanostructures in dielectrics by electron beam are derived using the localized plasmon theory in the random phase approximation at high frequency condition. These are applied to calculate inelastic scattering probabilities of electron beams and light emission intensities by the localized plasmon excitations for metal nanospheres and ultrathin films in dielectrics using the quasi-static and electric dipole approximations. It is also assumed that local dielectric functions for metals and dielectrics have step function shapes at the metal and dielectric interfaces. It is found that the electron beams are inelastically scattered by the localized surface and bulk plasmons with various excitation modes, but the light is emitted only from the localized surface plasmons with specific excitation modes within these approximations.

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Review Papers
  • Masaru Kato, Ichizo Yagi
    Type: Review Paper
    Subject area: Catalysis
    2020 Volume 18 Pages 81-93
    Published: March 14, 2020
    Released: March 14, 2020
    JOURNALS OPEN ACCESS

    Polymer electrolyte fuel cells (PEFCs) are a clean, sustainable device to convert chemical energy to electricity and can provide power for automobiles, trains, and ships. In PEFCs, the oxygen reduction reaction (ORR) occurs at the cathode and is catalyzed at electrocatalysts. The activity of ORR electrocatalysts is known to limit the overall performance of PEFCs because the ORR is more sluggish than the hydrogen oxidation reaction at the anode. In the state-of-the-art PEFC, platinum group metal (PGM)-based ORR electrocatalysts are used. Since PGMs are rare and expensive, highly active and durable non-PGM ORR electrocatalysts are required for widespread applications of PEFCs. In nature, metalloenzymes such as cytochrome c oxidase and multicopper oxidases efficiently catalyze the ORR and utilize multinuclear iron and/or copper complexes as active sites. The structure of these active sites and enzyme reaction mechanisms would give us design concepts of artificial non-PGM electrocatalysts for the ORR, possibly leading us to develop next-generation non-PGM electrocatalysts. Herein, recent research progress on understanding enzymatic ORR reaction mechanisms and developing non-PGM ORR electrocatalysts is reviewed from the viewpoint of bio-inspired approaches.

    Editor’s picks

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Conference—ALC '19—
Memorial
  • Wolf-Dieter Schneider, Friedrich Aumayr, Ulrike Diebold
    Type: Conference—ALC '19—
    Subject area: Memorial
    2020 Volume 18 Pages 8-11
    Published: February 06, 2020
    Released: February 06, 2020
    JOURNALS OPEN ACCESS
    Supplementary material

    Peter Varga has passed on October 27, 2018. His pioneering discoveries of chemical resolution at the atomic scale on surface alloys, atomic resolution of ultrathin alkali halides, nucleation of bcc iron in ultrathin films, and the microscopic structure of ultrathin alumina films stimulated worldwide research. In recognition of his outstanding scientific contributions, in December 2017 the Japanese Society for the Promotion of Science (JSPS) awarded him a prize for his distinguished contribution on the clarification of surface phenomena by atomic level investigations and the development of novel functional materials. This contribution highlights the life of Peter Varga as a scientist and as a person. With his elegance, his energy, his wit, and his generosity he was a close friend and role model to many of us, and showed us how to combine scientific curiosity and creativity with the lightness of being.

    Peter Varga at the 13th International Workshop on Inelastic Ion—Surface Collisions Fullsize Image
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Scientific Articles
  • Fumihiko Matsui, Seiji Makita, Hiroyuki Matsuda, Takahiro Ueba, Toshio ...
    Type: Conference—ALC '19—
    Subject area: Instrumentations and Techniques
    2020 Volume 18 Pages 18-23
    Published: February 08, 2020
    Released: February 08, 2020
    JOURNALS OPEN ACCESS

    Two-dimensional angle-resolved photoelectron spectroscopy is a powerful method to study the electronic structure of a crystal surface. The latest version of the angle-resolved photoelectron spectroscopy analyzer was installed at the BL6U of the UVSOR-III Synchrotron. This spectrometer consists of a hemispherical electron analyzer equipped with a mechanical deflector and a mesh electrostatic lens close to the sample to make the size of acceptance cone tunable. A constant-energy photoelectron angular distribution of the valence band dispersion cross section in the large wave number region can be efficiently obtained by applying a negative bias voltage to the sample and using a mechanical deflector. Here, the three-dimensional bulk band and the surface state dispersion mappings of Au(111) surface are presented to show the performance of the current photoelectron spectroscopy experimental station. We revisited the dual observation of bulk and surface electronic structures at this kinetic energy regime.

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  • M. H. Al Rashid, A. Dipu, Y. Nishikawa, H. Ogihara, Y. Inami, S. Obuch ...
    Type: Conference—ALC '19—
    Subject area: Environmental and Energy Technology
    2020 Volume 18 Pages 24-27
    Published: February 15, 2020
    Released: February 15, 2020
    JOURNALS OPEN ACCESS
    Supplementary material

    SiO2-supported NiP binary catalysts show high activity for the non-oxidative coupling of methane (NOCM) reactions, one of the most difficult but important catalytic reactions. We have studied the SiO2-supported NiP binary catalysts by extended X-ray absorption fine structure (EXAFS) with different Ni : P ratios. NiP binary catalyst with the composition of Ni : P = 1 : 1 was the most active among the three different compositions. EXAFS showed that the NiP catalyst with Ni : P = 1 : 1 had a Ni2P structure. The structure was stable after the high temperature (1173 K) NOCM reaction conditions for 12 h. It is interesting that Ni2P shows high catalytic activities in many other reactions such as hydrodesulfurization, hydrogen evolution reaction, and so on. It may be due to the appropriate electronic and geometrical modification of a Ni active site by P.

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  • Ryohei Tanaka, Tetsuya Kishimoto, Takayuki Yoshimura, Shu Kurokawa, Ak ...
    Type: Conference—ALC '19—
    Subject area: Instrumentations and Techniques
    2020 Volume 18 Pages 28-31
    Published: February 20, 2020
    Released: February 20, 2020
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    A Monte Carlo numerical simulation is performed to clarify the reason why an atomic resolution microscope such as a scanning tunneling microscope (STM) cannot give accurately a ppm (parts per million) concentration of elements quantitatively. A relation between the sampling amount and the accuracy has been found. At least 109 atoms are needed to be sampled in order to discriminate the 49 and 50 ppm elemental concentrations. This Monte Carlo result has also been applied to the elemental analysis methods such as ICPAES (inductively-coupled plasma atomic emission spectrometry) and TXRF (total reflection X-ray fluorescence) to clarify the appropriate amount of sampling amount for required precision of quantitative elemental analysis.

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  • Kenichi Ozawa, Kazuhiko Mase
    Type: Conference—ALC '19—
    Subject area: Electronic Properties
    2020 Volume 18 Pages 41-47
    Published: February 29, 2020
    Released: February 29, 2020
    JOURNALS OPEN ACCESS

    Electronic modification of O-terminated ZnO(000-1) and Zn-terminated ZnO(0001) by ethanethiol (C2H5SH) adsorption was investigated by angle-resolved photoelectron spectroscopy (ARPES) and X-ray photoelectron spectroscopy (XPS). Ethanethiol dissociates on both surfaces at room temperature to form C2H5S and H. The saturation coverage of ethanethiol is nearly three times larger on ZnO(0001) than on ZnO(000-1). This suggests that Zn atoms exposed to the surface should act as adsorption and dissociation sites. Adsorption on the (000-1) surface induces large downward band bending and accompanies a Zn 4s-derived metallic state at the center of the surface Brillouin zone. This proves that ethanethiol is a good electron donor on ZnO(000-1). Contrastingly, ethanethiol on ZnO(0001) hardly affects the energetic position of the ZnO band so that surface metallization is not brought about.

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  • Christian Tusche, Ying-Jiun Chen, Lukasz Plucinski, Claus M. Schneider
    Type: Conference—ALC '19—
    Subject area: Electronic Properties
    2020 Volume 18 Pages 48-56
    Published: February 29, 2020
    Released: February 29, 2020
    JOURNALS OPEN ACCESS

    Photoelectron spectroscopy is our main tool to explore the electronic structure of novel material systems, the properties of which are often determined by an intricate interplay of competing interactions. Elucidating the role of this interactions requires studies over an extensive range of energy, momentum, length, and time scales. We show that immersion lens-based momentum microscopy with spin-resolution is able to combine these seemingly divergent requirements in a unifying experimental approach. We will discuss applications to different areas in information research, for example, resistive switching and spintronics. The analysis of resistive switching phenomena in oxides requires high lateral resolution and chemical selectivity, as the processes involve local redox processes and oxygen vacancy migration. In spintronics topological phenomena are currently a hot topic, which lead to complex band structures and spin textures in reciprocal space. Spin-resolved momentum microscopy is uniquely suited to address these aspects.

    Editor’s picks

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  • Hiroki Momono, Hiroyuki Matsuda, László Tóth, Hir ...
    Type: Conference—ALC '19—
    Subject area: Instrumentations and Techniques
    2020 Volume 18 Pages 57-61
    Published: March 05, 2020
    Released: March 05, 2020
    JOURNALS OPEN ACCESS

    We have realized a simple and compact new two-dimensional electron analyzer “a VD-WAAEL analyzer” using a variable-deceleration-ratio wide-acceptance-angle electrostatic lens (VD-WAAEL). Using an electron gun and an angle measurement tool, we confirmed that a two-dimensional angular distribution could be measured at once over a large solid angle of ±45°. We also confirmed that energy analysis could be performed with an aperture. Here a high energy resolution of ∼0.23% was obtained by using the aperture size of 0.8 mmø at the 40° position. Moreover, a magnified image of SUS316 #100 mesh was successfully measured. The magnification ratio was 25, which was in good agreement with the calculation.

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  • Hiroyuki Kageshima, Shengnan Wang, Hiroki Hibino
    Type: Conference—ALC '19—
    Subject area: Crystal Growth
    2020 Volume 18 Pages 70-75
    Published: March 07, 2020
    Released: March 07, 2020
    JOURNALS OPEN ACCESS

    To elucidate bottom-up fabrication of heterostructures of two-dimensional materials such as graphene and h-BN, C atom adsorption on Cu(111) surface partially covered with h-BN or graphene is studied by using the first-principles method with van der Waals correction. It is found that the C monomer more difficultly locates under h-BN than under graphene or on bare Cu, while the C monomer also more hardly diffuses under graphene than under h-BN or on bare Cu. In addition, formation of C dimers is more difficult under graphene than under h-BN or on bare Cu. These results suggest that we can control the heterostructure growth by modulating growth condition. It is further found that the shape of h-BN or graphene flake on the Cu surface depends on whether the edge is terminated with hydrogen (H) or not. Because the bond formation energy of edges with H atoms are different between h-BN and graphene, it is indicated that appropriate choice of H condition will lead us to the intentional formation of lateral and vertical heterostructures.

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  • Keiko Yamada, Yuya Murata, Taku Moronaga, Kazushi Hayashi, Chikara Ich ...
    Type: Conference—ALC '19—
    Subject area: Thin Films
    2020 Volume 18 Pages 94-99
    Published: March 19, 2020
    Released: March 19, 2020
    JOURNALS OPEN ACCESS

    The zeta (ζ) factor proposed by Watanabe and Williams [M. Watanabe and D. B. Williams, J. Microsc. 221, 89 (2006)] is a fundamental parameter for quantitative X-ray analysis with consideration of X-ray absorption using scanning transmission electron microscopy in combination with silicon drift detectors (STEM-SDD). In this study, the ζ-factors for Fe and Mn in iron-based alloy systems were determined by two thin-film approaches, namely, the “lift-off method” and the “direct deposition method”. The Mn content in the Fe-Mn alloy obtained by using the ζ-factor, which was measured with Mn thin films directly deposited on a transmission electron microscopy (TEM) mesh grid, was in good agreement with the composition determined by fluorescent X-ray analysis. Determination of the accurate film thicknesses is essential for the accurate measurement of the ζ-factors. A layered structure and a directly deposited thin film is found effective for a standard sample to prevent bending and overlapping of samples. It is proved that the proposed method to fabricate the standard sample is useful for quantitative X-ray analysis with existing STEM-SDD system.

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  • Masashi Nojima, Hiroto Mita, Kazuki Hara
    Type: Conference—ALC '19—
    Subject area: Instrumentations and Techniques
    2020 Volume 18 Pages 101-105
    Published: March 21, 2020
    Released: March 21, 2020
    JOURNALS OPEN ACCESS

    Selection of the cluster size of an ion beam is a key factor for controlling sputtering speeds or the damaged layer of polymer materials. We developed a two rotating electric fields (REFs) type of mass spectrum (MS) filter or analyzer using a novel principle. The REF-MS can continuously separate typical sizes of cluster ions by optimizing the frequencies of the REFs. In this study, we developed an electrospray ionization (ESI) gun column to optimize the cluster sizes of a water ion beam by REF-MS. Annular ring patterns of size-selected clusters were observed using optimized focusing frequencies on typical water molecule clusters. The patterns were compared with the results of the finite difference simulation method. We sputtered a spin-coated polymer film using a size-filtered water cluster ion beam. A sputtering crater was observed on the polystyrene film sputtered by the size-optimized water cluster ion beam. Here, we discuss the cluster size dependence of sputtering speeds for an ion beam for typical numbers of water clusters.

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  • Hideya Mizuno, Kento Kubo, Kentaro Kojima, Masatoshi Kotera
    Type: Conference—ALC '19—
    Subject area: Electronic Properties
    2020 Volume 18 Pages 106-109
    Published: March 21, 2020
    Released: March 21, 2020
    JOURNALS OPEN ACCESS

    It is known that insulating films charge up positively or negatively under electron beam irradiation. The potential distribution produced at the specimen surface can be measured by our homemade electrostatic force microscope installed in a scanning electron microscope. A global charging, found within several mm from the irradiation area is made by fogging electrons, which are generated by multiple backscattering events between the specimen and the objective lens plate. Since the most of the energy of fogging electrons is less than 5 eV, the global charging can be suppressed at the specimen by applying −5 V to the specimen. On the other hand, the local charging at the irradiation point shows a positive charging in a small dose, but as the dose increases a negative charging is obtained. By increasing the dose further, a positive charging is found. We found two non-charging conditions of insulating film under electron beam irradiation.

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  • Ryota Ito, Masato Akatsuka, Muneaki Yamamoto, Tetsuo Tanabe, Tomoko Yo ...
    Type: Conference—ALC '19—
    Subject area: Catalysis
    2020 Volume 18 Pages 110-115
    Published: March 21, 2020
    Released: March 21, 2020
    JOURNALS OPEN ACCESS
    Supplementary material

    We have prepared La2O3 supported Ga2O3 (Ga2O3/La2O3) photocatalyst to improve the photocatalytic activity of Ga2O3 for CO2 reduction with water under ultraviolet light irradiation without a noble metal cocatalyst. Significant improvement on both CO2 reduction and water splitting was attained compared with those for non-supported Ga2O3 and La2O3. The improvement is attributed to the transformation of the La2O3 surface to NaLa(CO3)2 during the photocatalytic reduction tests in aqueous solution of NaHCO3. NaLa(CO3)2 was preferentially formed on the surface of La2O3 without changing Ga2O3 resulting in the structure of Ga2O3 supported by NaLa(CO3)2. Once NaLa(CO3)2 fully covered the surface of La2O3, the high catalytic activity was kept long.

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  • So-Hee Kang, Shinnosuke Kishi, Kohei Matsumura, Bunbunoshin Tomiyasu, ...
    Type: Conference—ALC '19—
    Subject area: Instrumentations and Techniques
    2020 Volume 18 Pages 116-120
    Published: April 02, 2020
    Released: April 02, 2020
    JOURNALS OPEN ACCESS

    The concept of three-dimensional (3D) shave-off secondary ion mass spectrometry (SIMS) is that enables to obtain the depth information of the sample simultaneously with the mass information using the vertical axis of a two-dimensional position-sensitive detector in the mass analyzer. In this study, we simulated the trajectory of secondary ions sputtered from a virtual sample in the 3D shave-off SIMS system and investigated the magnification ratio of the ions. The simulation results showed that we could distinguish the depth position of the secondary ions sputtered from a sample by the detected position in our concept of 3D shave-off SIMS.

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  • Long Cheng, Z. J. Ding
    Type: Conference—ALC '19—
    Subject area: Nano-Science and -Technology
    2020 Volume 18 Pages 121-125
    Published: April 04, 2020
    Released: April 04, 2020
    JOURNALS OPEN ACCESS

    We present two quantum trajectory approaches for the simulation of electron backscatter diffraction (EBSD). The quantum trajectory approaches are based on Schrödinger equation and they yield excellent agreements with experimental patterns. Meanwhile, they are particle models that allow ones to intuitively understand the processes of electron diffraction in a classical way. Besides, the approaches have significant advantages in computation efficiency. Because of the accuracy, intuitiveness, and efficiency, the trajectory approaches allow us a deeper understanding of the physical processes of EBSD.

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  • Muhammad Arifin, Takahiro Matsumoto, Abdul-Muizz Pradipto, Toru Akiyam ...
    Type: Conference—ALC '19—
    Subject area: Interdisciplinary
    2020 Volume 18 Pages 133-138
    Published: April 09, 2020
    Released: April 09, 2020
    JOURNALS OPEN ACCESS

    Optical properties of several transition metals, namely 3d (Fe, Ni, Co, Cu), 4d (Ru, Rh, Pd, Ag), and 5d (Os, Ir, Pt, Au) metals, for the application of surface plasmon resonance (SPR) were investigated. Using first-principles density functional theory method, we calculated the optical conductivities and the dielectric constant by including contributions from intraband and interband transitions. The calculated results for all systems reproduce the experimental trends qualitatively. The contribution of the Drude model is very dominant at low energy levels and gives a tail effect to the spectrum. Peaks in optical conductivity can be observed, which can be related to interband transitions. The SPR reflectance curve based on the Kretschmann configuration has further been simulated.

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  • Yoshimi Horio, Hitoshi Nakahara, Junji Yuhara, Yuji Takakuwa
    Type: Conference—ALC '19—
    Subject area: Structure
    2020 Volume 18 Pages 139-145
    Published: April 09, 2020
    Released: April 09, 2020
    JOURNALS OPEN ACCESS

    The Auger electron intensities of Si-LVV and Ag-MNN from a Si(111)7×7 and a Si(111)√3×√3-Ag surfaces were measured for varying glancing angles of the incident electron beam in reflection high-energy electron diffraction, known as the beam rocking Auger electron spectroscopy (BRAES). The energy of incident electron beams used was 10 and 5 keV. The intensity anomalies observed in these BRAES profiles on the surface wave resonance condition were more pronounced for the 5-keV incident beam than for the 10-keV beam. It was found from BRAES profiles of the Si(111)√3×√3-Ag surface by the 5-keV incident beam that the intensity enhancements of Si-LVV differed from those of Ag-MNN at the [112] incidence, but were similar at the [101] incidence. This result can be interpreted qualitatively by the wave field periodicity parallel to the surface.

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  • Hayato Yamashita, Nobuhiro Handa, Yuma Higashiura, Masayuki Abe
    Type: Conference—ALC '19—
    Subject area: Instrumentations and Techniques
    2020 Volume 18 Pages 146-151
    Published: April 11, 2020
    Released: April 11, 2020
    JOURNALS OPEN ACCESS
    Supplementary material

    Dynamic behaviors of atoms on a material surface are important processes for catalytic reactions and crystal growth. Visualizing their processes will contribute to understanding reaction mechanisms and the process of surface structural formation. Scanning tunneling microscopy (STM) is a powerful tool to investigate the surface structure of solid materials and has been used to observe the atomic structures of various important materials such as metals and semiconductors. However, the scan speed of conventional scanning tunneling microscopes is too slow to capture dynamic processes of surface atoms in real time. In this study, we developed a new scanner for high-speed STM (HS-STM). This scanner is constructed from a flexure structure actuating in the x and y directions and a small piezoactuator actuating an STM tip in the z direction. To enhance the actuation bandwidth, the tip holder was minimized and the flexure was hardened. We successfully imaged atomic structures on both highly oriented pyrolytic graphite under ambient conditions and a Si(111) under ultrahigh vacuum at 1 frame s−1 using the developed HS-STM scanner.

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  • Koji Asaka, Satoshi Toma, Yahachi Saito
    Type: Conference—ALC '19—
    Subject area: Nano-Materials
    2020 Volume 18 Pages 159-163
    Published: April 23, 2020
    Released: April 23, 2020
    JOURNALS OPEN ACCESS

    Long linear carbon chains (LCCs) encapsulated in carbon nanotubes (CNTs) were produced on a film scale by field emission discharge of CNT films. LCCs inside CNTs were characterized by Raman spectroscopy and transmission electron microscopy. After an electric discharge of a CNT film cathode, long LCCs encapsulated in single-wall CNTs as well as double-wall and triple-wall CNTs were formed in the film. The length of LCCs is longer than 30 nm (i.e., more than 230 carbon atoms). Not only a single LCC but also two or three LCCs in parallel inside a CNT were found. Raman spectra showed prominent peaks, called “LCC bands”, in a region from 1790 to 1860 cm−1 originating from longitudinal optical phonons of LCCs. The observation of strong LCC bands are due to resonance Raman scattering, i.e., the excitation photon energies between 1.85—2.54 eV match with energy gaps of the long LCCs inside CNTs.

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  • Kokoro Yoshioka, Muneaki Yamamoto, Tetsuo Tanabe, Tomoko Yoshida
    Type: Conference—ALC '19—
    Subject area: Catalysis
    2020 Volume 18 Pages 168-174
    Published: April 25, 2020
    Released: April 25, 2020
    JOURNALS OPEN ACCESS
    Supplementary material

    It is well known that Ag loaded Gallium oxide (Ag/Ga2O3) promotes photocatalytic CO2 reduction to CO. However, the role of the Ag co-catalyst in the CO2 reduction has not been clarified. We have intended to find the relationship between the state of Ag loaded on Ga2O3 and their activity for the photocatalytic CO2 reduction. To achieve this, we have tried to control and stabilize the loading state of Ag on Ga2O3 during their use for the photocatalytic CO2 reduction by adding methanol as a reducing agent. It is confirmed that methanol stabilizes the particle sizes of Ag nanoparticles (Ag-NPs) loaded on Ga2O3 under the photocatalytic CO2 reduction condition and is hardly decomposed to produce CO. Using Ga2O3 loaded with size-controlled Ag-NPs as a photocatalyst for the CO2 reduction, it is found that Ag-NPs with their sizes within 10—30 nm are active sites for the photocatalytic CO2 reduction and the catalytic activity linearly increases with the increase of the number density of Ag-NPs. However, a higher Ag loading amount over 1.0 wt% promotes aggregation of Ag to be larger metal particles over 70 nm which are not active for the CO2 reduction.

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  • Nguyen Thi Trinh, Yu Sheng, Shinya Asakura, Khuat Thi Thu Hien, Goro M ...
    Type: Conference—ALC '19—
    Subject area: Thin Films
    2020 Volume 18 Pages 175-179
    Published: May 02, 2020
    Released: May 02, 2020
    JOURNALS OPEN ACCESS

    Contribution of main chains and side chains of unrubbed polyimide films with steroidal structure side chains to second harmonic generation (SHG) response was studied by varying their molar fraction of side-chain diamine. The SHG intensity in Pin/Pout polarization (P-polarization input and P-polarization output) configuration does not depend strongly on the molar fraction. This indicates that both the main chains and side chains at the surface contribute similarly to the SHG intensity. The SHG intensity in Sin/Pout polarization configuration normalized by that of Pin/Pout polarization configuration was the smallest for the molar fraction of side-chain diamine of 0%. This fact indicates that the microscopic nonlinear dipoles are standing nearly upright at the surface of the film consisting only of the main chains, while their orientational spread is wider when the side chains are involved.

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  • Goro Mizutani, Zhipeng Yong, Khuat Thi Thu Hien, Harvey N. Rutt
    Type: Conference—ALC '19—
    Subject area: Reaction and Dynamics
    2020 Volume 18 Pages 180-184
    Published: May 07, 2020
    Released: May 07, 2020
    JOURNALS OPEN ACCESS

    We used sum frequency generation (SFG) spectroscopy to study the desorption of hydrogen on the stepped Si(111) surface with a miscut angle of 9.5° toward the [112] direction in ultra-high vacuum. The terrace peak was observed at 2085 cm−1 and the vertical step mode of dihydride was observed at 2098 cm−1 for the ssp-polarization (s-polarized SFG, s-polarized visible, and p-polarized infrared light) combination. The intensity reduction of these two peaks was monitored directly as a function of time at sample temperatures of 593 K. The rate of reduction was faster for the step dihydride peak than for the terrace monohydride peak.

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  • Hirotaka Asai, Takayuki Tanaka, Hidekazu Murata, Eiji Rokuta
    Type: Conference—ALC '19—
    Subject area: Nano-Materials
    2020 Volume 18 Pages 185-189
    Published: May 09, 2020
    Released: May 09, 2020
    JOURNALS OPEN ACCESS

    Atomic scale tungsten (W) pyramids coated with monolayer films of noble metals can be produced on the apex of a W tip sharpened by means of chemical etching. In this work, we produced Pd- and Au-coated nanopyramids using W tips with different apex curvature radii as a substrate and examined the yield ratios of the nanopyramid formation. When the curvature radius is larger than 15 nm, both Pd- and Au-coated W nanopyramids grow. However, when the radius is less than 15 nm, only Au-coated nanopyramids grow. We propose that the preferential growth for the Au case is associated with previous calculation results demonstrating that the difference in the anisotropy of the surface energy between the Au/W(111) and Au/W(211) systems is substantial [S. P. Chen, Surf. Sci. 274, L619 (1992)].

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