e-Journal of Surface Science and Nanotechnology
Online ISSN : 1348-0391
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Showing 1-50 articles out of 83 articles from the selected issue
Regular Papers
  • Natarajan Elangovan, Sivashanmugam Pugalmani, Arthanari Srinivasan, Na ...
    Type: Regular Paper
    Subject area: Interdisciplinary
    2018 Volume 16 Pages 5-13
    Published: February 10, 2018
    Released: February 10, 2018
    JOURNALS FREE ACCESS

    A novel nanocomposite coating containing poly (N-vinyl carbazole) (PVK) and zirconia (ZrO2) nanoparticles was synthesized using chronoamperometry. The effect of ZrO2 nano particles into the PVK matrix and its mechanical, corrosion protection ability on 316L SS substrates were studied. The incorporation of the nanoparticles was endorsed by attenuated total reflectance infrared spectroscopy (ATR-IR) and EDAX analysis. The spheroidal morphology and core-shell structure were revealed with scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The thermal studies exhibited the stability of coating. The anticorrosion performance of PVK-ZrO2 nanocomposite coatings in 3.5 weight (wt.)% NaCl medium was performed with potentiodynamic polarization technique and electrochemical impedance spectroscopy (EIS) studies. The corrosion rate of PVK-ZrO2 nanocomposite coated 316L SS was found to be 0.58 times lower than uncoated 316L SS and a significant decrease in corrosion potential was realized from -0.211 VSCE for uncoated 316L SS to 0.112 VSCE for PVK-ZrO2 nanocomposite coated 316L SS substrates. The results of this study clearly ascertain that the PVK-ZrO2 nanocomposite has an outstanding potential to protect 316L SS against corrosion in a 3.5 wt.% NaCl environment. [DOI: 10.1380/ejssnt.2018.5]

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  • Kousik Dutta
    Type: Regular Paper
    Subject area: Electronic Properties
    2018 Volume 16 Pages 14-19
    Published: February 10, 2018
    Released: February 10, 2018
    JOURNALS FREE ACCESS

    Development of environmentally benign methods for the synthesis of nanoparticles is an evolving important branch of nanotechnology. Inorganic-organic hybrid nanocomposites are synthesized by dispersing nanosized CdS in the conducting polypyrrole (PPY) matrix. The samples are characterized by X-ray diffraction, transmission and scanning electron microscopes and UV-VIS spectrophotometer. The wavelength of optical absorption peak of CdS nanoparticle increases from 430 nm to 470 nm with the decrease of polypyrrole concentration. Studies on dc electrical conductivity as a function of temperature suggest that three dimensional Mott’s hopping process occurs in CdS-Polypyrrole nanocomposites. The incorporation of CdS nanoparticles enhances the barrier height. The barrier height increases with the content of CdS. The observed nonlinear current-voltage characteristics are satisfactorily explained using the Schottky type barriers. [DOI: 10.1380/ejssnt.2018.14]

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  • Ahmed Ali Mohammad Monzur-Ul-Akhir, Masayuki Mori, Koichi Maezawa
    Type: Regular Paper
    Subject area: Crystal Growth
    2018 Volume 16 Pages 20-26
    Published: February 21, 2018
    Released: February 21, 2018
    JOURNALS FREE ACCESS

    The single crystalline InSb and GaSb thin films on the same Si(111) substrate is an essence of CMOS device fabrication. In this study, the growth of InSb has been observed on InGaSb intermediate layer grown on High Quality (HQ) GaSb buffer layer of single crystalline nature. In this case, InxGa1–xSb was initially grown on HQ GaSb/Si(111)-√3 × √3-Ga surface following a two-step growth method. The controlled and precise flux ratio of Ga and Sb enabled HQ GaSb layer to grow without twins. For InxGa1–xSb intermediate layer, In ratio x ranged from 0.90 to 0.75 for samples S1–S4 with a step 0.05. To analyze the growth nature and surface morphology, Reflection High Energy Electron Diffraction (RHEED), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) have been performed and studied. It is concluded that InSb epitaxial surfaces have shown better smoothness and fewer defects towards Gallium increase. The growth nature in this case for both InSb epitaxial layer and InGaSb intermediate layer were coherent where HQ GaSb buffer layer was effective in decreasing twins. Some complementary samples were prepared to support the assumptions made before starting the experiments. Finally, the possibility of single crystalline InSb and GaSb thin films on the same Si(111) substrate has been demonstrated. [DOI: 10.1380/ejssnt.2018.20]

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  • Hiroshi Kuwahata, Yuki Murata, Naoki Hashimoto, Riyuya Segawa
    Type: Regular Paper
    Subject area: Reaction and Dynamics
    2018 Volume 16 Pages 27-35
    Published: February 21, 2018
    Released: February 21, 2018
    JOURNALS FREE ACCESS

    An atmospheric-pressure argon (Ar) plasma jet was generated with a frequency of 10 kHz, an applied voltage of 4 kV, and an Ar gas flow rate of 10 L/min. When an aluminum (Al) thin film that was vacuum-deposited on a glass substrate was irradiated with the atmospheric-pressure Ar plasma jet in air for 60 s at an irradiation distance of 2 mm, the surface of the Al thin film was hydrophilized in a circular area with a diameter of 23 mm, which was larger than that of the plasma (6 mm). It was found that the superhydrophilization first occurred at the periphery of the irradiated area (∼5–10 mm from the center of the irradiated area) and then in the area irradiated directly by the plasma (≤∼5 mm from the center of the irradiated area) on the Al thin film. In the previous research on the atmospheric-pressure plasma jet irradiation of Al, the plasma reached Al, and it was reported that the hydrophilicity only improved in the area irradiated directly by the plasma. On the other hand, our plasma in this study did not reach Al. In spite of this, the hydrophilicity improved in the area irradiated directly by the plasma and in the periphery of the irradiated area. On the basis of the results of X-ray photoelectron spectroscopy (XPS), the hydrophobic organic compounds that adsorbed on the surface of the Al thin film are considered to have been removed by the ozone (O3) generated by the interaction between the plasma and oxygen (O2) molecules in air. From the O3 concentration distribution obtained using O3 test strips, the reason for the faster superhydrophilization in the peripheral area than in the irradiated area was found to be that the peripheral area had the higher concentration of O3. [DOI: 10.1380/ejssnt.2018.27]

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  • Yuki Koda, Hirosuke Sumida, Satoshi Ogawa, Chie Tsukada, Hirofumi Nama ...
    Type: Regular Paper
    Subject area: Nano-Materials
    2018 Volume 16 Pages 36-40
    Published: March 03, 2018
    Released: March 03, 2018
    JOURNALS FREE ACCESS

    Rhodium nanoparticles were deposited by the evaporation method on a silicon wafer. The process used He gas in a Rh evaporation chamber that was connected to the load-lock chamber of BL6N1 at Aichi Synchrotron Radiation Center (Aichi SR). NO gas was introduced into the evaporation chamber, and the deposited Rh nanoparticles were exposed to NO with and without an ambient atmosphere to study the effect of O2 on the electronic properties of the Rh nanoparticles and the behavior of NO molecules using synchrotron-radiation X-ray photoelectron spectroscopy (SR-XPS). The diameter of the Rh nanoparticles was estimated by transmission electron microscopy to be 2.7±0.6 nm. The XPS analysis indicates that the deposited Rh nanoparticles before NO exposure were in the metallic state. After exposure to NO, a part of the outermost surface of the Rh nanoparticles changed into Rh oxide, and NO molecules, atomic N and O species, and NO2 were detected. On the other hand, after exposure to NO in ambient air, the surface of the Rh nanoparticles was preferentially oxidized. In addition, a few NO molecules were adsorbed on the surface of Rh, and a small amount of the adsorbed NO that reacted with the surface oxygen turned into NO2. [DOI: 10.1380/ejssnt.2018.36]

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  • Yadong Chai, Tadashi Yamaguchi, Tania Guadalupe Penaflor Galindo, Moto ...
    Type: Regular Paper
    Subject area: Bio-Science and -Technology
    2018 Volume 16 Pages 156-162
    Published: May 16, 2018
    Released: May 16, 2018
    JOURNALS FREE ACCESS

    The culture behavior of the osteoblast-like cells on the calcium phosphate (CP) films interacted with phospholipid vesicle (PV) were investigated. The different CP crystalline phases were prepared from the biological solutions such as simulated body fluid (SBF) and unique SBF, which were called as CP/PV and U-CP/PV films, respectively, and these were used after the sterilization. The protein adsorption amounts on the CP/PV films were higher than that of the PV film. The osteoblast-like cells cultured on the U-CP/PV film had the longest length along with the extension direction. The density of the osteoblast-like cells adhered on the CP/PV and U-CP/PV films were higher, suggesting the preferential adhesion on the surfaces. The differentiated osteoblasts on the films were visualized by the alkaline phosphatase and Alizarin-red-S staining methods. It was suggested that the osteoblasts cultured on the CP/PV and U-CP/PV films exhibited the possibility of the high osteogenic activities. Therefore,the PV-interacted CP films prepared from the biological solutions are useful for the osteoblast culture plates. [DOI: 10.1380/ejssnt.2018.156]

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  • Yun Kim, Masanori Owari
    Type: Regular Paper
    Subject area: Instrumentations and Techniques
    2018 Volume 16 Pages 190-192
    Published: May 25, 2018
    Released: May 25, 2018
    JOURNALS FREE ACCESS

    Field ion microscope (FIM) is an instrument used to analyze the structure of specimen surface at an atomic scale. In recent years, a position-sensitive detector (PSD) has been used as a detector in FIM. By using the PSD, much information can be obtained, such as the number of released ion from each position. In this work, we studied the ionization in FIM measurement using pulsed laser. In the FIM measurement using the pulsed laser, ions with specific time structure relative to the laser pulse were detected, and the FIM image of these ions was similar to that of a normal FIM image, although the spatial resolution decreased. Furthermore, we observed delay in ionization at the parallel axis along the irradiation direction of the pulsed laser, and we believed that this was caused by the delay in the ionization due to the heat transfer. From the experimental results, we proposed that the heat caused by the pulsed laser was involved in the ionization, in contrast to conventional field ionization. [DOI: 10.1380/ejssnt.2018.190]

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  • Kazuya Miura, Fumikazu Kimata, Ryo Watanabe, Choji Fukuhara
    Type: Regular Paper
    Subject area: Catalysis
    2018 Volume 16 Pages 209-213
    Published: May 31, 2018
    Released: May 31, 2018
    JOURNALS FREE ACCESS

    To study the physicochemical properties of supported Pt catalysts, we performed DFT calculations for the supported Pt3 clusters with various oxides. We determined that the chemical potential (μ) of the supported Pt cluster (μPt/MOx) could be described by averaging the μ values of the isolated Pt3 clusters and support oxides without Pt species (μMOx ). The proportional value of the molar fraction of supported Pt species (mol%) should be used as the weighted factors for calculation of the average value. As a result, μPt/MOx could be expected to become μMOx for the actual Pt catalysts, because of their low Pt loadings (∼1 wt% ∼ 0.1 mol%). [DOI: 10.1380/ejssnt.2018.209]

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  • So-Hee Kang, Yun Kim, Bunbunoshin Tomiyasu, Masanori Owari
    Type: Regular Paper
    Subject area: Instrumentations and Techniques
    2018 Volume 16 Pages 214-217
    Published: May 31, 2018
    Released: May 31, 2018
    JOURNALS FREE ACCESS

    The shave-off scan method is a unique secondary ion mass spectrometry (SIMS) section processing technique using a gallium focused ion beam (Ga FIB). The sample had a distinctive cross-sectional shape after shave-off scanning, and the slope of the cross section related to the incident angle of the beam that affects sputtering yield. This study investigates sputtering yield as a function of shave-off scan speeds based on cross-sectional shapes examined using a scanning electron microscope (SEM). To conduct a more detailed comparison of the cross sections, the SEM images were converted to an X, Y coordinate system using an in-house program. The sputtering yield decreased as scan speed decreased and incident angle increased. This result opposed the results obtained using conventional raster scanning, and beam profiles could be predicted from the cross-sectional shapes. [DOI: 10.1380/ejssnt.2018.214]

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  • Fumihiko Ogata, Eri Nagahashi, Yuhei Kobayashi, Takehiro Nakamura, Nao ...
    Type: Regular Paper
    Subject area: Environmental and Energy Technology
    2018 Volume 16 Pages 229-235
    Published: June 07, 2018
    Released: June 07, 2018
    JOURNALS FREE ACCESS

    This paper shows the efficacy of the combination of ozonation and adsorbent treatment in removing cationic and anionic dyes (methylene blue and acid orange 7, respectively) and chemical oxygen demand (COD) from wastewater. The adsorbent was prepared with coffee ground, rice bran, and soybean bran as sources of waste biomass, and was calcined at 1000°C. We demonstrated three methods, namely, singular ozonation, singular adsorbent treatment, and the combination of the two treatments. The removal percentage of dye and COD by ozonation was greater than that by adsorbent treatment. However, the incomplete removal of dye and COD through ozonation suggested that singular treatment is not sufficient for this purpose. Subsequently, we evaluated the combination treatment; the removal percentage of dye and COD by this treatment was higher than those from the singular treatments, which indicates that the adsorption and degradation capacities were enhanced. In addition, the calcined adsorbent could be used at least four times. These results show the novelty and utility of this treatment for the removal of dye and COD from wastewater containing dye. [DOI: 10.1380/ejssnt.2018.229]

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  • Vyomesh R Buch, Sushant K Rawal, Amit Kumar Chawla
    Type: Regular Paper
    Subject area: Thin Films
    2018 Volume 16 Pages 289-293
    Published: June 16, 2018
    Released: June 16, 2018
    JOURNALS FREE ACCESS

    Tungsten oxide (WO3) films have been deposited on glass substrates by radio frequency magnetron sputtering of tungsten target. We examined the effect of oxygen flow rate in argon and helium atmosphere on the structural, optical, and electrochromic properties of WO3 films. When helium gas is replaced with argon, the particle sizes and the band gap will get affected. Band gap values were obtained over a range of 2.62 eV to 3.09 eV. The atomic mass of the sputtering gas also plays a prime role in changing the primary crystallite size, orientation, as well as band gap. We could relate the crystallization of tungsten atoms with low oxygen flow rate when films are deposited in helium instead of argon due to Penning ionization. [DOI: 10.1380/ejssnt.2018.289]

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  • Xiaoyin Yi, Qing Yang
    Type: Regular Paper
    Subject area: Nano-Materials
    2018 Volume 16 Pages 310-312
    Published: June 23, 2018
    Released: June 23, 2018
    JOURNALS FREE ACCESS

    Nanoporous copper/nickel (NP-Cu/Ni) were prepared by electroless plating of Ni-P on nanoporous copper (NP-Cu). The influence of concentration ratio of lactic acid to citric acid on the morphologies and mechanical properties of NP-Cu/Ni was investigated. The results showed that the ligament width increased after electroless plating and the three-dimensional bicontinuous ligament-channel structure was retained. The mechanical properties were improved. NP-Cu/Ni prepared using concentration ratio of 30 g/L : 20 g/L demonstrated the best comprehensive performance. [DOI: 10.1380/ejssnt.2018.310]

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  • Masakazu Ichikawa
    Type: Regular Paper
    Subject area: Nano-Science and -Technology
    2018 Volume 16 Pages 329-338
    Published: July 21, 2018
    Released: July 21, 2018
    JOURNALS FREE ACCESS

    A theory of localized bulk and surface plasmons for metal nanostructures in dielectrics is derived in the random phase approximation at the high frequency condition. The induced charge density in dielectrics is added to the induced charge density by the plasmons appeared in the previously reported integral equation for the scalar potential. The integral equation is composed of the local electron density in metal nanostructures, the local electric susceptibility of dielectrics and the retarded Green's function. In the quasi-static approximation, the integral equation is transformed into the one that is composed of the local dielectric functions for metals and dielectrics and the Coulomb potential. Using a model where the local dielectric functions have step function shapes at the interfaces between the metals and dielectrics, it can be analytically solved in the quasi-static approximation. The localized surface plasmon frequencies and the light emission intensities are then derived for metal nanostructures such as ultrathin layer, nanowire, and nanosphere. [DOI: 10.1380/ejssnt.2018.329]

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  • Natee Sirisit, Daiki Kido, Yuki Wakisaka, Hiroko Ariga-Miwa, Satoru Ta ...
    Type: Regular Paper
    Subject area: Instrumentations and Techniques
    2018 Volume 16 Pages 387-390
    Published: September 01, 2018
    Released: September 01, 2018
    JOURNALS FREE ACCESS

    We have shown a possibility of multi-atom resonant X-ray Raman (MARX-Raman) spectroscopy by measuring the N K-edge loss spectrum of TaN at Ta L3-edge and C K-edge loss spectrum of Er(C5H5)3 at Er L1-edge. When the excitation X-ray energy was tuned to the Ta L3-edge and inelastic scattering spectra were recorded around 400 eV loss corresponding to the N K-edge Raman region, we found a clear enhancement of emission spectrum. The same enhancement was observed in C K-edge Raman region in Er(C5H5)3. These experimental results have indicated the possibility of MARX-Raman phenomenon which may lead to a new in situ and bond-specific XAFS spectroscopy for low Z elements. [DOI: 10.1380/ejssnt.2018.387]

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  • Allan Abraham B. Padama, Wilson Agerico Diño, Motoi Wada, Katsu ...
    Type: Regular Paper
    Subject area: Electronic Properties
    2018 Volume 16 Pages 391-395
    Published: September 20, 2018
    Released: September 20, 2018
    JOURNALS FREE ACCESS

    We studied the adsorption of H on Cs/W(110) by performing density functional theory (DFT) based total energy calculations to determine the influence of H on Cs stability on the surface. For reference, we also independently examined the adsorption of H and Cs on clean W(110). We found that the adsorption energies of both H and Cs decrease in the presence of the other. H adsorbs more strongly in H/W(110) as compared to the coadsorbed system H/Cs/W(110). We observe the same trend for Cs adsorption in Cs/W(110) and H/Cs/W(110) systems. Due to the greater electronegativity of H as compared to Cs, increasing the H coverage further weakens Cs adsorption on the W surface. The results suggest that the presence of H could lead to the desorption of Cs from the surface and thus, it is necessary to reevaluate the designs of Cs/W systems used in negative hydrogen production applications. [DOI: 10.1380/ejssnt.2018.391]

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  • Norio Inui
    Type: Regular Paper
    Subject area: Nano-Science and -Technology
    2018 Volume 16 Pages 400-405
    Published: October 04, 2018
    Released: October 04, 2018
    JOURNALS FREE ACCESS

    We theoretically investigate the desorption process of an argon atom from a vibrating nanographene sheet. A high eigenfrequency of a graphene membrane owing to a small mass density per area and a large Young's modulus of graphene enable increasing the velocity of an atom enough to escape from the attractive interaction between the atom and graphene in a short time by accelerating the graphene sheet. We present the dependence of the velocity of ejected atom on the frequency and amplitude of the graphene membrane and consider an application to heating gas in small cavity. [DOI: 10.1380/ejssnt.2018.400]

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  • Dipak L. Gapale, Sandeep A. Arote, Ratan Y. Borse
    Type: Regular Paper
    Subject area: Thin Films
    2018 Volume 16 Pages 419-426
    Published: October 25, 2018
    Released: October 25, 2018
    JOURNALS FREE ACCESS

    The pure TiO2 thin films were successfully deposited onto a glass substrate by using modified spray pyrolysis system. The TiO2 thin films were deposited at temperature 350°C using Titanium trichloride precursor solutions of concentration 0.075 M, 0.1 M, and 0.125 M. Also, TiO2 thin films with precursor solutions of concentration 0.1 M were deposited at different deposition temperature 350°C, 400°C, and 450°C. The prepared samples were further annealed at 500°C for 2 h to improve crystallinity. The XRD study revealed that the deposited TiO2 thin films were polycrystalline and showed anatase phase with pre-dominant (101) peak. The crystallite size calculated from XRD was found to increase with increase in precursor solution concentration. The mathematical model to calculate crystallite size and film thickness were developed and the predicted results were compared with experimental results. The experimentally calculated crystallite size and thickness was in good agreement with the predicted results. The details of mathematical model and calculations TiO2 thin films for were discussed in detail. [DOI: 10.1380/ejssnt.2018.419]

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Rohrer Medal Lecture
  • Alfred J. Weymouth, Daniel Wastl, Franz J. Giessibl
    Type: Rohrer Medal Lecture
    Subject area: Nano-Science and -Technology
    2018 Volume 16 Pages 351-355
    Published: August 02, 2018
    Released: August 02, 2018
    JOURNALS FREE ACCESS

    It's hard to imagine that we can take a splinter and sharpen it down to the atomic level. It's even more impressive that we can bring this sharp tip close to a surface, scan it over the surface, and be sensitive to the tiny forces between the apex atom and individual atoms on the surface. Measuring and interpreting these forces is the goal of high-resolution atomic force microscopy (AFM). We perform frequency-modulation AFM (FM-AFM), in which we oscillate the tip and record the change in frequency as a measure of the interaction with the surface. FM-AFM performed in vacuum with stiff sensors has lead to amazing discoveries. Now, we are returning to the challenge of imaging samples in device- and biologically-relevant conditions. This contribution summarizes work that was performed in the Giessibl group to image with atomic resolution in ambient and liquid environments. We demonstrated atomic resolution with the qPlus sensor on KBr, and followed this with investigations on graphitic surfaces. We have also shown single-atomic defects and steps on the calcite surface. [DOI: 10.1380/ejssnt.2018.351]

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Conference -ISSS-8-
  • Yuichi Uchida, Masahiro Hara, Asami Funatsu, Fuyuki Shimojo
    Type: Conference -ISSS-8-
    Subject area: Thin Films
    2018 Volume 16 Pages 1-4
    Published: January 31, 2018
    Released: January 31, 2018
    JOURNALS FREE ACCESS

    Titania nanosheets (TNSs) are expected to lead to higher photocatalytic performance than bulk TiO2 because its high reactivity arises from the two-dimensional structure. While their electronic properties are considered to be easily affected by structural vacancies, the effects of vacancies in TNSs on the photocatalytic performance are not clear. In order to study them, we have performed first-principles molecular dynamics simulations for structure models of TNSs with several vacancies. First, we have calculated the electronic density of states and bandgap energies Eg. It has been found that Eg of our structure modes of TNSs with vacancies are larger than bulk anatase. This tendency is consistent with the experimentally observed relationship of Eg between TNSs and anatase. It has been clarified from non-adiabatic calculations that the existence of vacancies in TNSs causes spatial charge separation and leads to longer recombination time. [DOI: 10.1380/ejssnt.2018.1]

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  • Yuri Maruko, Tania Guadalupe Penaflor Galindo, Motohiro Tagaya
    Type: Conference -ISSS-8-
    Subject area: Bio-Science and -Technology
    2018 Volume 16 Pages 41-48
    Published: March 17, 2018
    Released: March 17, 2018
    JOURNALS FREE ACCESS

    We investigated the coating process of mesostructured triblock copolymer-tetraethoxysilane (P123-TEOS) and mesoporous silica (MPS) films on a bioinert poly(dimethylsiloxane) (PDMS) with the different cross-linker concentrations through an oxygen-plasma treatment to evaluate the mesostructure formation and adsorption ability of proteins (albumin, fibrinogen, γ-globulin, fetal bovine serum). In the PDMS preparation, the cross-linker concentration affected the polymer network formation and the siliceous layer was formed on the most-surfaces by the plasma treatment. The transparent siliceous films of P123-TEOS and MPS were successfully covered on the cross-linked PDMS without voiding and the coating film thicknesses were ca. 100 nm. The FT-IR spectra indicated that the change from P123-TEOS to MPS occurred with preserving the PDMS chemical bonds by the calcination. Especially, the XRD patterns and nitrogen adsorption and desorption isotherms of the MPS on PDMS indicated the mesostructured film formation with preserving the ordered nanopore structures (BJH pore sizes: 1.6-4.2 nm, BET surface areas: 394-602 m2/g). The hydrophobic PDMS surfaces became more wettable by the coating. The adsorption amounts of acidic proteins (albumin, fibrinogen) were changed by the coating. For the fibrinogen, the P123-TEOS on PDMS exhibited the most adsorption sites. Therefore, the bio-interactive properties of the PDMS surfaces were demonstrated based on the coating processes. [DOI: 10.1380/ejssnt.2018.41]

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  • Ryota Ono, Peter Krüger
    Type: Conference -ISSS-8-
    Subject area: Electronic Properties
    2018 Volume 16 Pages 49-52
    Published: March 31, 2018
    Released: March 31, 2018
    JOURNALS FREE ACCESS

    A computational method is devised for calculating angle-resolved photoelectron spectra using a plane-wave basis and repeated-slab geometry. The method is tested with a one-dimensional model with a rectangular potential well. The model parameters are adjusted to reproduce electronic structure of graphene at the Γ point of the Brillouin zone, as obtained from density functional theory. Photoemission final states with proper boundary conditions are constructed from linear combinations of supercell eigenstates such as to match the free wave at the center of the vacuum region. These states, calculated with a moderate plane-wave cut-off, agree very well with the exact wave function. The computed photoemission intensity differs strongly from the popular (single) plane-wave approximation and shows a pronounced energy dependence. [DOI: 10.1380/ejssnt.2018.49]

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  • Yuji Baba, Iwao Shimoyama
    Type: Conference -ISSS-8-
    Subject area: Thin Films
    2018 Volume 16 Pages 53-59
    Published: March 31, 2018
    Released: March 31, 2018
    JOURNALS FREE ACCESS

    Desorption of positive ions as well as neutrals from bulk cesium chloride has been investigated in the moderate temperature (< 500°C), which is lower than its melting point (645°C). At this moderate temperature range, neutral Cs was slightly desorbed, but desorption of Cs+ ions was not observed. On the other hand, when the positive potential was applied to the sample, Cs+ ions were desorbed with abnormally high intensity. The ratio of the desorbed ions to neutrals (ICs+ /ICs) showed a maximum at around 415°C. Based on the analysis using the Saha-Langmuir model, the observed high Cs+ desorption yield under electric field was interpreted by the changes in the surface work function caused by the phase transition of CsCl. The abnormally high Cs+ desorption yield at such low temperature under electric field would be applied to various fields such as ion production in accelerator and separation of cesium from complex systems through dry process. [DOI: 10.1380/ejssnt.2018.53]

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  • Osamu Endo, Hiroyuki Ozaki, Masashi Nakamura, Kenta Amemiya
    Type: Conference -ISSS-8-
    Subject area: Structures
    2018 Volume 16 Pages 60-65
    Published: April 07, 2018
    Released: April 07, 2018
    JOURNALS FREE ACCESS

    The presence of a self-assembled monolayer (SAM) of dioctadecyl sulfide (DOS) on a Au(111) electrode affects the underpotential deposition (UPD) of copper in sulfuric acid solution. The first stage of the UPD, i.e., formation of the √3 × √3 R30° lattice comprising the honeycomb structure of copper, is delayed by the DOS SAM of the lower-density phase, in which the chain axis is parallel to the surface. Neutral molecules are preferentially adsorbed on the Au(111) electrode surface at around the potential of zero charge (pzc), which is approximately −0.1 V (vs. Hg|Hg2SO4) in sulfuric acid solution. The adsorption of copper ions at this potential is inhibited by the DOS SAM, which delays the successive Cu-UPD process in the first stage. In contrast, the DOS SAM of the higher-density phase, in which the chain axis is standing upright, inhibits the entire UPD process. [DOI: 10.1380/ejssnt.2018.60]

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  • Hiroyuki Kagitani, Seijiro Kinoshita, Osamu Kubo, Kazuki Takahashi, Hi ...
    Type: Conference -ISSS-8-
    Subject area: Thin Films
    2018 Volume 16 Pages 66-71
    Published: April 07, 2018
    Released: April 07, 2018
    JOURNALS FREE ACCESS

    The structure of platinum (Pt) silicide products grown on Si(001) substrate by Pt deposition at 600°C was analyzed using coaxial impact collision ion scattering spectroscopy. The resulting surface always had two kinds of products, nanowires and islands. The Pt2Si crystals with four low index surface planes were took up as candidates for the products, and it was found that the nanowires and islands of the Pt silicide were composed of Pt2Si with (010) and Si-terminated (001) as surface planes, respectively. The surface energy calculation performed using density functional theory calculation indicated that the Si-terminated Pt2Si(001) had the lowest energy among the examined surfaces, which is consistent with the fact that islands are the major products on the surface. [DOI: 10.1380/ejssnt.2018.66]

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  • André E. B. Amend, Tomohiro Matsui, Hideki Sato, Hiroshi Fukuya ...
    Type: Conference -ISSS-8-
    Subject area: Electronic Properties
    2018 Volume 16 Pages 72-75
    Published: April 12, 2018
    Released: April 12, 2018
    JOURNALS FREE ACCESS

    Graphene is a two-dimensional sheet of carbon atoms, which consists of two π-electron sublattices. At zigzag-type edges, there is an imbalance between the two sublattices that creates an edge-localized state, which causes a sharp increase of the local density of states (LDOS) at the Dirac point. Simulations of single vacancies on graphene, that also cause localized states, show that the LDOS is suppressed on both sides of the peak energy, where the suppression range depends on the extent of the sublattice imbalance. Here, we studied edges of hexagonal nanopits with monatomic depth prepared by hydrogen-plasma etching of graphite surfaces with scanning tunneling microscopy and spectroscopy at T = 4.7 K and 78 K. In addition to a prominent peak near the Dirac point, we found a clear suppression of the LDOS on both sides of the peak over a ±100 mV range, which has not been observed before. Analogous to single vacancies, such a LDOS can be caused by the high sublattice imbalance, which indicates that the fabricated edges are substantially rich in zigzag structure. An exponential decay of the spectral weight of the edge-state has been observed with a decay length of 1.2 ± 0.3 nm at T = 78 K, which is consistent with previous works. [DOI: 10.1380/ejssnt.2018.72]

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  • Hiromasa Fujii, Kaori Sasaki, Yusuke Wakabayashi, Hiroo Tajiri, Kazumo ...
    Type: Conference -ISSS-8-
    Subject area: Structures
    2018 Volume 16 Pages 76-78
    Published: April 12, 2018
    Released: April 12, 2018
    JOURNALS FREE ACCESS

    Self-assembled monolayers (SAMs) are used for adjusting the work function of metal electrodes in organic devices. Since the energy level difference between the HOMO or LUMO and the work function affects the electron injection through the metal-organic interfaces, fine tuning of the work function is of importance. To control the work function from external environment, external large electric field on low-density SAMs is reported to be effective. In order to obtain a direct evidence for the structural switching of the SAM, X-ray reflectivity measurements were performed. The result shows that the molecular tilting of 10° is induced by the external voltage application. [DOI: 10.1380/ejssnt.2018.76]

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  • Hidetaka Watanuki, Kei Mitsuhara, Masaru Takizawa
    Type: Conference -ISSS-8-
    Subject area: Thin Films
    2018 Volume 16 Pages 79-83
    Published: April 14, 2018
    Released: April 14, 2018
    JOURNALS FREE ACCESS

    Organic semiconductors with a high carrier mobility can be realized by controlling a growth direction of the thin film. A new method to control the growth direction is using a temperature gradient. Molecular orientation strongly influences on the carrier mobility. Therefore, the molecular orientation of 2,7-dioctyl benzothieno benzothiophene (C8-BTBT) thin films grown under a temperature gradient, has been evaluated by X-ray absorption fine structure measurements. It is considered that the C8-BTBT has a molecular orientation with standing up on the substrate, and is aligned to the temperature gradient direction. [DOI: 10.1380/ejssnt.2018.79]

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  • Yoshimi Horio, Ryo Yamazaki, Junji Yuhara, Yuji Takakuwa, Masamichi Yo ...
    Type: Conference -ISSS-8-
    Subject area: Structure
    2018 Volume 16 Pages 88-92
    Published: April 18, 2018
    Released: April 18, 2018
    JOURNALS FREE ACCESS

    Using reflection high-energy electron diffraction (RHEED), we demonstrate the behavior of a wave field formed on a graphite crystal surface. The sample used is highly oriented pyrolytic graphite, which is a polycrystalline (mosaic crystal) with a few micrometers-sized domain rotated on a plane. One-beam dynamical calculation is proved to be effective for analyzing the distance between the atomic planes. One-beam dynamical calculation is also used to obtain a wave field, which is incident electron density distribution, for surface normal direction. The characteristic behavior of the wave field at Bragg conditions is demonstrated by the Auger electron intensity of carbon excited by RHEED incident electron beam. This can be measured by changing the glancing angle using beam rocking Auger electron spectroscopy (BRAES). It has been found that the anomalous intensities in the measured BRAES profile almost correspond to the calculated wave field intensities on the atomic planes. [DOI: 10.1380/ejssnt.2018.88]

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  • Takaaki Kawamura
    Type: Conference -ISSS-8-
    Subject area: Structure
    2018 Volume 16 Pages 97-100
    Published: April 20, 2018
    Released: April 20, 2018
    JOURNALS FREE ACCESS

    A fast phase retrieval approach from reflection high energy electron diffraction (RHEED) intensities is proposed for monitoring growing surfaces almost in real time. The approach is based on a hybrid input-output algorithm and the processing time is reduced in two ways by taking peculiarities to RHEED intensities during growth. One is to reduce the number of sampling points along the incident beam direction in which the number is much larger than that in the normal direction due to grazing incidence of the beam. The other is to reduce the number of iterations in the retrieving process. The resulting real space objects are well reproduced providing surface morphology during growth approximately in 0.1 s. [DOI: 10.1380/ejssnt.2018.97]

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  • Mohammad Tawheed Kibria, Tatsushi Nomitsu, Takeshi Nakagawa, Seigi Miz ...
    Type: Conference -ISSS-8-
    Subject area: Thin Films
    2018 Volume 16 Pages 101-104
    Published: April 26, 2018
    Released: April 26, 2018
    JOURNALS FREE ACCESS

    We report the magnetic dead layer at the interfaces between Fe and Si(111) surfaces. We prepared two ultrathin iron-silicides, c(8×4) prepared at 900 K and p(2×2) at 700 K, and clean reconstructed 7×7 surface for the silicon templates. By using magneto-optical Kerr effect, we found that at room temperature the ferromagnetic order appears at 5.5 ML, 8.2 ML, and 10.9 ML for Fe/c(8×4) silicide, Fe/p(2×2) silicide, and Fe/Si(111)-7×7 surface, respectively. From the thickness dependent magnetization measurements, we decided the magnetic dead layer for Fe/c(8×4) silicide, Fe/p(2×2) silicide, and Fe/Si(111)-7×7 to be 3.0 ML, 5.0 ML, and 7.5 ML, respectively. Our results indicate that the c(8×4) iron silicide surface prevents further silicide formation more effectively than the p(2×2) silicide and Si(111)-7×7 surface. [DOI: 10.1380/ejssnt.2018.101]

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  • Satoru Yoshimura, Yoshihiro Nishimoto, Satoshi Sugimoto, Masato Kiuchi ...
    Type: Conference -ISSS-8-
    Subject area: Catalysis
    2018 Volume 16 Pages 105-110
    Published: April 26, 2018
    Released: April 26, 2018
    JOURNALS FREE ACCESS

    Indium nanoparticles were deposited on zeolite powders using a pulse arc plasma system. The resulting materials were capable of catalyzing an organic chemical reaction, namely the Friedel-Crafts alkylation between benzhydryl chloride and anisole. Varying the electrical capacitance in the plasma system (360 μF or 1080 μF) resulted in some changes in the indium concentration on the sample surface and in the size of the indium nanoparticles, but the catalytic ability of the material was largely unaffected. [DOI: 10.1380/ejssnt.2018.105]

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  • Yuki Fukaya
    Type: Conference -ISSS-8-
    Subject area: Structure
    2018 Volume 16 Pages 111-114
    Published: April 28, 2018
    Released: April 28, 2018
    JOURNALS FREE ACCESS

    Recently, two-dimensional atomic sheets composed of group-IV elements, which are expected to possess intriguing properties in terms of electronic and spin-related phenomena, have been fabricated on various substrate surfaces. The atomic configurations of atomic sheets are varied depending on the bonding character of the elements and the interaction with substrates. In particular, the magnitude of buckling and the spacing between the atomic sheet and the substrate are crucial to elucidate the origin of its properties. In this review, we report the structure determinations of graphene, silicene, and germanene on the particular substrate surfaces by using total-reflection high-energy positron diffraction (TRHEPD) technique. [DOI: 10.1380/ejssnt.2018.111]

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  • Chikashi Egawa
    Type: Conference -ISSS-8-
    Subject area: Catalysis
    2018 Volume 16 Pages 115-118
    Published: April 28, 2018
    Released: April 28, 2018
    JOURNALS FREE ACCESS

    As a model surface of Co-Mo alloy catalysts for ammonia decomposition, Co deposited Mo(112) surface has been investigated by XPS, UPS, LEED, and kinetic measurement using a high-pressure reactor. Co deposition on Mo(112) surface followed by annealing at 1000 K shows a (1×1) LEED pattern with the split along the [-1-11] direction and a characteristic emission at −2.9 eV for Co-Mo d-band hybridization. The decomposition of ammonia on Co/Mo(112) surface proceeds accompanied by nitride formation. The reaction rate exhibits half order dependence on ammonia pressure with an activation energy of 101 kJ/mol, which is in good agreement with the results on alumina supported Co-Mo alloy catalysts. [DOI: 10.1380/ejssnt.2018.115]

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  • Andris Šutka, Martin Timusk, Urmas Joost, Reinis Ignatans, Mikh ...
    Type: Conference -ISSS-8-
    Subject area: Nano-Materials
    2018 Volume 16 Pages 119-121
    Published: May 02, 2018
    Released: May 02, 2018
    JOURNALS FREE ACCESS

    Optical properties of diluted narrow band gap magnetic semiconductor nanowire colloids are controlled by modest magnetic fields under 100 Oe. High aspect ratio NiFe2O4 nanowires are used to achieve responsiveness to magnetic field, light absorption and -scattering. Visible light reflectance of the diluted colloids can be either increased or decreased depending on the nanowire alignment relative to the direction of the light propagation. The prepared colloids can be applied as magneto-optical switches or as smart window devices. [DOI: 10.1380/ejssnt.2018.119]

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  • Masahito Niibe, Noritaka Takehira, Takashi Tokushima
    Type: Conference -ISSS-8-
    Subject area: Electronic Properties
    2018 Volume 16 Pages 122-126
    Published: May 02, 2018
    Released: May 02, 2018
    JOURNALS FREE ACCESS

    We have measured the soft X-ray absorption and emission spectra of near B-K and C-K absorption edges of highly oriented pyrolytic graphite (HOPG) doped with a small amount (0.32 at.%) of boron (B), including incident/takeoff angle dependence. The main peak intensities at the B-K edge around 182 eV were almost independent on the change of takeoff angle. On the other hand, the satellite peak around 185 eV becomes larger as the takeoff angle becomes smaller. Based on this result, unlike the previous assignment of the main peak predicted from the quantum chemical calculation (π orbitals), it is reasonable to attribute the main peak to the σ orbitals. The takeoff angle dependence of the B-K emission is similar to the angle dependency of the C-K emission of undoped HOPG. Based on this and the theoretical consideration, it is presumable that the doped B atom does not intercalate between the layers of HOPG; it replaces the C atom of the hexagonal network structure and has a wave function similar to that of C atoms (sp2 type hybridized orbital). [DOI: 10.1380/ejssnt.2018.122]

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  • Kenji Motohashi, Tomoki Tachikawa, Takashi Uchida, Kensei Kawamura
    Type: Conference -ISSS-8-
    Subject area: Nano-Science and -Technology
    2018 Volume 16 Pages 127-131
    Published: May 03, 2018
    Released: May 03, 2018
    JOURNALS FREE ACCESS

    In this study, we performed a mass-spectrometric study of cluster ions scattered on glass surfaces covered with ferrocene molecules under the incidence of 4.8 keV-C60q+ (q = 1 and 2) ions. A couple of optical flats covered with 11-ferrocenyl-1-undecanethiol self-assembled monolayer surfaces (Fc-thiol-SAMs) faced each other with a shape called a tapered planar channel (TPC) and C60 ions entered the wider opening gap. The mass and charge of each ion exiting from the narrower gap of the TPC were successfully analyzed using time-of-flight mass spectrometry combined with the parallel plate charge separation method. When the TPC was tilted by 2° with respect to the C60 ion beam axis, the mass distribution peak shifted to ∼730 u. Furthermore, we conducted an elemental analysis of the scattered particles deposited on a Si substrate by inductively coupled plasma mass spectrometry. A significant increase in the amount of iron atoms was confirmed for the deposited substrate, as compared with non-deposited substrates. [DOI: 10.1380/ejssnt.2018.127]

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  • Yasuhiro Senda, Janne Blomqvist, Risto Nieminen
    Type: Conference -ISSS-8-
    Subject area: Nano-Science and -Technology
    2018 Volume 16 Pages 132-136
    Published: May 03, 2018
    Released: May 09, 2018
    JOURNALS FREE ACCESS

    We analyze the stability of the atomic configurations of tips in the adhesion process in noncontact atomic force microscopy (AFM) using a potential energy surface (PES). We calculate the PES for two types of atomic configurations of the tip as typical cases of reconstruction and irreversible change during the adhesion process. The stability of the tips after atomic contact with the surface is explained on the basis of the calculated PESs, which are affected by the strength of the atomic bond between the tip and the surface. It is shown from the computational model for the AFM that an unstable tip leads to a larger energy dissipation compared to that for a stable tip. [DOI: 10.1380/ejssnt.2018.132]

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  • Y. Matsuzawa, S. Kaneko, S. Fujii, T. Nishino, M. Kiguchi, K. Tsukagos ...
    Type: Conference -ISSS-8-
    Subject area: Nano-Science and -Technology
    2018 Volume 16 Pages 137-141
    Published: May 09, 2018
    Released: May 09, 2018
    JOURNALS FREE ACCESS

    Photo-induced chemical reaction of p-aminobenzenthiol (ABT) was investigated using the lithographically fabricated mechanically controllable break junction (MCBJ). The ABT single-molecule junction was formed at the nanogap of the MCBJ and the formation was confirmed by the electronic transport measurement including current versus bias voltage characteristics. Light irradiation at the nanogap revealed that ABT molecules were subject to photo-induced dimerization, which was confirmed by measuring SERS spectrum. In addition, we tuned the gap size using MCBJ technique and demonstrated that the photo-induced dimerization was absent for the molecules at the wide gap. [DOI: 10.1380/ejssnt.2018.137]

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  • Atsushi Matsuoka, Hirotoshi Matsumura, Masafumi Odaka, Nobuaki Ogawa, ...
    Type: Conference -ISSS-8-
    Subject area: Reaction and Dynamics
    2018 Volume 16 Pages 142-144
    Published: May 12, 2018
    Released: May 12, 2018
    JOURNALS FREE ACCESS

    In this study, we recorded the transitional response in terms of terahertz transmittance of zeolitic imidazole framework-8 [Zn(2-methylimidazolate)2, ZIF-8] at 2.0 THz as a function of exposure time to gaseous propane and n-butane. The transmittance at 2.0 THz increased as gas adsorbed onto the ZIF-8. Conversely, during a nitrogen purge, transmittance decreased as the alkane gas desorbed. We estimated time constants for the adsorption and desorption of the two gases by comparing the plots of their responses. We also demonstrated the potential of using a combination of ZIF materials and terahertz technology as a novel gas analyzer. [DOI: 10.1380/ejssnt.2018.142]

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  • S. Kobayashi, S. Kaneko, S. Fujii, T. Nishino, M. Kiguchi, K. Tsukagos ...
    Type: Conference -ISSS-8-
    Subject area: Nano-Materials
    2018 Volume 16 Pages 145-149
    Published: May 12, 2018
    Released: May 12, 2018
    JOURNALS FREE ACCESS

    We have investigated the current-voltage (I-V) curves of the benzenedithiol (BDT) single molecular junction as a function of stretch length of the junction. The BDT single molecular junction was prepared with the nano fabricated Au electrodes using the mechanically controllable break junction (MCBJ). The conductance of the BDT single molecular junction gradually decreased with the stretching length of the junction. We analyzed the obtained I-V curves based on the two different models; the single channel model and the field emission model. Based on the single channel model, it was revealed that the decrease in conductance was mainly caused by the decreases in the metal-molecule coupling and that the HOMO approached to the Fermi level with the decrease in the electrode separation. The energy shift of the HOMO was supported by the analysis based on the field emission model. [DOI: 10.1380/ejssnt.2018.145]

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  • Federico Grillo, Rory Megginson, Jenny Christie, Stephen M. Francis, N ...
    Type: Conference -ISSS-8-
    Subject area: Thin Films
    2018 Volume 16 Pages 163-171
    Published: May 19, 2018
    Released: May 19, 2018
    JOURNALS FREE ACCESS

    The structure and surface chemistry of ultrathin metallic films of one metal on another are strongly influenced by factors such as lattice mismatch and the formation of near-surface alloys. New morphologies may result with modified chemical properties which in turn open up different routes for molecular adsorption, desorption and surface functionalization, with important consequences in several fields of application.
    The Cu/Au(111) system has received the attention of many studies, only a few however have been performed in ultra-high vacuum (UHV), using surface sensitive techniques. In this contribution, the room temperature deposition of copper onto the (22×√3)-Au(111) surface, from submonolayer to thick film, is investigated using scanning tunnelling microscopy (STM).
    The onset of copper adsorption is seen to occur preferentially at alternate herringbone elbows, with a preference for hcp sites. With increasing coverage, copper-rich islands exhibit a reconstructed surface reminiscent of the clean Au(111) herringbone reconstruction. Disordered, pseudo-ordered and ordered surface layers are observed upon annealing. Models for the initial adsorption/incorporation mechanism, formation of adlayers and evolution with increasing coverage and annealing are qualitatively discussed. Further, the reactivity of copper-doped Au(111) systems is considered towards the adsorption of organic molecules of interest in nanotechnology and in catalytic applications. [DOI: 10.1380/ejssnt.2018.163]

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  • Kenta Amemiya, Masako Sakamaki
    Type: Conference -ISSS-8-
    Subject area: Thin Films
    2018 Volume 16 Pages 186-189
    Published: May 25, 2018
    Released: May 25, 2018
    JOURNALS FREE ACCESS

    Effects of electric fields on magnetization of ferromagnetic Ni films grown on a Cu(001) single crystal covered with antiferromagnetic NiO overlayer are investigated by means of X-ray absorption spectroscopy (XAS), X-ray magnetic circular dichroism (XMCD), and magneto-optical Kerr effect (MOKE). The growth of the NiO overlayer on the Ni film is confirmed by XAS, and it is revealed by XMCD and MOKE that the NiO/Ni films show a spin reorientation transition from in-plane to perpendicular magnetization with increasing Ni thickness. It is also observed that the coercive field of the Ni films increases as the NiO thickness increases, possibly due to the interaction with antiferromagnetic NiO. Remanent magnetization of the Ni film is found to be modified by the application of electric fields. The possible origin of the electric-field effects is discussed, and some change in magnetic anisotropy of the Ni film is suggested. [DOI: 10.1380/ejssnt.2018.186]

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  • Shun Hasegawa, Yuji Kunisada, Norihito Sakaguchi
    Type: Conference -ISSS-8-
    Subject area: Nano-Materials
    2018 Volume 16 Pages 193-200
    Published: May 25, 2018
    Released: May 25, 2018
    JOURNALS FREE ACCESS

    In this study, we calculated the diffusion of an Fe atom on graphene and various light-element (B, N, O, Si, P, and S)-doped graphene supports, using first-principles calculations based on density functional theory. We focused on dopants that could suppress the detachment and diffusion of an Fe atom. Such doped graphene supports would have strong potential in high-durability fuel cell catalysts and hydrogen storage materials. The Fe atom adsorbs on pristine graphene via ionic bonding. The bonding between the Fe atom and pristine graphene is very weak, and it has a low adsorption energy of −0.61 eV. Doped graphene contains unoccupied localized orbitals. B-, O-, Si-, and P-doped graphene show high adsorption energies of −1.70 eV, −2.70 eV, −1.46 eV, and −1.38 eV, respectively. Thus, these graphene supports could suppress the detachment of Fe nanoclusters and nanoparticles. We demonstrate that these doped graphene supports with high adsorption energies also have high diffusion barriers, which suppresses the agglomeration of Fe nanoclusters and nanoparticles. We conclude that B-, O-, Si-, and P-doped graphene are promising supports for enhancing the adsorption lifetime of Fe nanoclusters and nanoparticles. [DOI: 10.1380/ejssnt.2018.193]

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  • Theodore L. Einstein, Ludwig Bartels, Josue R. Morales-Cifuentes
    Type: Conference -ISSS-8-
    Subject area: Structure
    2018 Volume 16 Pages 201-208
    Published: May 25, 2018
    Released: May 25, 2018
    JOURNALS FREE ACCESS

    This paper modestly expands an invited talk at ISSS-8 with the same title. After reviewing the relevant interactions between adsorbates on substrates with metallic surface states [especially Cu(111)], it focuses on organic adsorbates. Of particular interest are those which form honeycomb lattices with pores of various sizes. The nature of the confined states derived from the surface-state electrons is discussed as their effect on admolecules inside the pores. [DOI: 10.1380/ejssnt.2018.201]

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  • Xiang Meng, Peiling Yuan, Yasuhiro Hayakawa, Kenta Sasaki, Keisuke Tsu ...
    Type: Conference -ISSS-8-
    Subject area: Nano-Materials
    2018 Volume 16 Pages 218-224
    Published: June 07, 2018
    Released: May 31, 2018
    JOURNALS FREE ACCESS

    Si-based nanosheet bundles were formed by Ca-atom extraction from CaSi2 crystals by thermal treatment using FeCl2, FeCl3, NH4Cl, and MgCl2. The morphological property of the Si-based nanosheet bundles was examined. Though the Si-based nanosheets were formed under the stated thermal treatment conditions using FeCl3, the formation of iron-oxide phases was accelerated at higher temperatures and longer duration times for the highest thermal treatment temperatures using FeCl2. Thinner and thicker nanosheets were obtained using NH4Cl and MgCl2, respectively. The morphological properties of the Si-based nanosheet bundles were compared to each other and their formation mechanism was discussed in terms of the thermal instability of the chlorides, their vapor pressure and thermal treatment temperature profiles. [DOI: 10.1380/ejssnt.2018.218]

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  • Toshitaka Aoki, Kei Mitsuhara, Masaru Takizawa
    Type: Conference -ISSS-8-
    Subject area: Nano-Materials
    2018 Volume 16 Pages 225-228
    Published: June 07, 2018
    Released: June 07, 2018
    JOURNALS FREE ACCESS

    The growth mode of Cu nanoparticles deposited on the rutile TiO2(110) surfaces have been investigated by high-resolution medium energy ion scattering (MEIS). The observed MEIS spectra are well reproduced assuming the hemispherical and two-dimensional islands. The MEIS results indicated that the two-dimensional islands of Cu nanoparticles grow initially up to Cu coverage of 0.3 ML and then three-dimensional islands growth become dominant. Interestingly, growth mode is the same tendency for both reduced TiO2 (R-TiO2) and oxygen-rich TiO2 (O-TiO2). These results indicate that Cu has grown as a Volmer-Weber growth mode for TiO2 system and that Cu nanoparticles are formed as both 2D- and 3D- islands on R- and O-TiO2. [DOI: 10.1380/ejssnt.2018.225]

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  • Yuichi Sugizaki, Hiroki Motoyama, Kazuyuki Edamoto, Kenichi Ozawa
    Type: Conference -ISSS-8-
    Subject area: Thin Films
    2018 Volume 16 Pages 236-241
    Published: June 07, 2018
    Released: June 07, 2018
    JOURNALS FREE ACCESS

    The electronic structure of the VO film grown on Ag(100) has been studied by photoelectron spectroscopy (PES) utilizing synchrotron radiation. The Ag(100) surface covered by the VO film formed by V deposition in O2 at 3.7 × 10−9 Torr and subsequent annealing at 450°C gave a (1 × 1) LEED pattern. In the PES spectra for the (1 × 1) VO film, the conduction band mostly composed of V 3d-components was observed at 0—2.5 eV. The valence band mostly composed of O 2p-components was formed overlapping with the substrate Ag 4d band, and the analysis of the resonant PES spectra revealed that the band existed at 4—10 eV. Both of the PES spectra for the VO film at room temperature and for that cooled to 4.86 K showed a clear cut-off at the Fermi edge, implying that the (1 × 1) VO film has a metallic electronic structure when the temperature is higher than 4.86 K. [DOI: 10.1380/ejssnt.2018.236]

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  • Akihide Hayashi, Yoshinori Ato, Kohei Tada, Hiroaki Koga, Takashi Kawa ...
    Type: Conference -ISSS-8-
    Subject area: Catalysis
    2018 Volume 16 Pages 242-246
    Published: June 07, 2018
    Released: June 07, 2018
    JOURNALS FREE ACCESS

    The surface oxidation of a Au@NiO core-shell catalyst is the key to its catalytic activity. In this density functional theory (DFT) study, we explain why the Au core promotes the oxidation of the NiO shell. The Au@NiO catalyst is represented by a slab model in which NiO(001) layers are placed on Au(001) substrates (NiO/Au). Ni vacancy and oxygen adsorption are examined as the surface oxidized state. Spin density analysis, as well as differential charge density analysis, shows that the oxidation of NiO/Au depletes the electrons in the Au—O antibonding orbitals at the interface, instead of creating holes in NiO. Thus, the highly-oxidized state of the NiO shell is stabilized by its interaction with the Au core. [DOI: 10.1380/ejssnt.2018.242]

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  • Yasushi Maeda, Kohei Tada, Shin-ichi Yamazaki
    Type: Conference -ISSS-8-
    Subject area: Environmental and Energy Technology
    2018 Volume 16 Pages 253-256
    Published: June 09, 2018
    Released: June 09, 2018
    JOURNALS FREE ACCESS

    Rhodium porphyrin complexes deposited on carbon support exhibit high activity for electrochemical CO oxidation. As such, they are good candidates for CO-tolerant catalysts in polymer electrolyte fuel cells. For the practical use of rhodium porphyrin complexes, however, their stability in water is of paramount importance. In this study, rhodium (III) octaethylporphyrin chloride was deposited on a highly oriented pyrolytic graphite substrate and observed by atomic force microscopy before and after water treatment. Although treatment with water changed the surface structure of RhOEP/HOPG, the face-on RhOEP layer remained intact. [DOI: 10.1380/ejssnt.2018.253]

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  • Masaharu Oshima, Daisuke Mori, Aki Takigawa, Akihiko Otsuki, Naoka Nag ...
    Type: Conference -ISSS-8-
    Subject area: Micro- and Nano-Fabrication
    2018 Volume 16 Pages 257-261
    Published: June 09, 2018
    Released: June 09, 2018
    JOURNALS FREE ACCESS

    SiC trench structures having a width of 0.6 μm and a depth of 2.0 μm are fabricated by reactive ion etching (RIE) using a gas mixture of SF6, Ar, and O2. Further, SiC trench structures are cleaved to expose the sidewall for the channel region of a trench MOSFET. These structures were analyzed by pin-point photoelectron spectroscopy using a 100 nm soft-X-ray beam. It is observed that around 2 nm-thick homogeneous carbon-rich layer containing 1—2% F forms on the SiC sidewalls. This may be caused due to the re-deposition of RIE reaction products, CF4 and SiF4, under appropriate conditions to fabricate the trench walls that are approximately vertical using RIE. Further, a carbon-rich layer having a thickness of about 2.4 nm is also formed on the bottom of the SiC trench, suggesting the possibility of selective etching of Si from the SiC substrates. The position of the dominant peak that is associated with the SiC component remains constant regardless of the trench depth, suggesting homogeneous band bending due to the RIE defects, which may explain the reason for no variation being observed in the gate oxide/SiC interface trap density values. Further, the band bending of 1.50 eV that is observed on the sidewall can be attributed to a positively charged carbon vacancy (VC+). [DOI: 10.1380/ejssnt.2018.257]

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