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Volume 2
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Regular Papers
  • Hiroshi Uetsuka, Hiroshi Onishi, Yu-ichi Harada, Hiroshi Sakama, Yukio ...
    Type: Regular Paper
    Subject area: Catalysis
    Volume 2 (2004) Pages 32-37
    Released: February 08, 2004
    JOURNALS FREE ACCESS
    Nanometer-sized particles of MoS2 were synthesized on (100), (001), and (110) surfaces of rutile TiO2. Molybdenum oxide was deposited on the TiO2 substrates and then sulfided to simulate the preparation of industrial catalysts. The nanoparticles which appeared on the sulfided surfaces were assigned to MoS2 particles. The topography of the nanoparticles was observed by atomic force microscopy (AFM) and by transmission electron microscopy (TEM). The number density of the nanoparticles was related to the surface energy of the substrates through the population of nucleation centers. On the TiO2(110) surface, AFM and TEM images assignable to MoS2 crystals edge-bonded to the substrate were observed. The coincidental lattice spacings of MoS2 and this particular surface were related to the observed edge-bonded growth. [DOI: 10.1380/ejssnt.2004.32]
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  • Toru Hirahara, Iwao Matsuda, Shuji Hasegawa
    Type: Regular Paper
    Subject area: Electronic Properties
    Volume 2 (2004) Pages 141-145
    Released: April 06, 2004
    JOURNALS FREE ACCESS
    The energy contour at Fermi level (Fermi surface) of the Si(111)√3×√3-Ag superstructure was measured in several surface Brillouin zones (SBZs) by high resolution angle-resolved photoemission spectroscopy (ARPES). Fermi rings centered at Gamma points were observed only in the second SBZs, but missing in the first SBZ. This phenomenon was successfully reproduced by a calculation of the optical transition matrix based on a simple tight-binding approximation for the surface topmost-layer Ag atoms; the intensity in the first SBZ is diminished by destructive interferences in the matrix elements ( i.e., photoemission structure factor). Thus with the known atomic orbital components of the surface structure, we can predict the photoemission intensity distribution and correctly understand the band structure. [DOI: 10.1380/ejssnt.2004.141]
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  • Takuya Kadohira, Jun Nakamura, Satoshi Watanabe
    Type: Regular Paper
    Subject area: Structures
    Volume 2 (2004) Pages 146-150
    Released: April 12, 2004
    JOURNALS FREE ACCESS
    We have investigated the atomic and electronic structures of the Au/Si(111)-α(√3 × √3)R30° surface using the first-principles calculations within the density functional theory in the generalized gradient approximation, focusing on honeycomb configurations. The energetically favored honeycomb model has a geometry that two Au atoms are located at H3 site on a Si substrate with missing top layer configuration. The formation energy of this model is less than that of the conjugate honeycomb-chained trimer (CHCT) one proposed by Ding et al. [Surf. Sci., 275, L691 (1992)] and that of the most stable configuration having the Au coverage of 1/3 ML in a certain range of chemical potential of Au. The observed energy band structure is not completely reproduced in our calculation using the honeycomb configuration as well as the CHCT one. On the other hand, the scanning tunneling microscope image simulated for the stable honeycomb model agrees with the observed ones. Our results, together with the recent experimental evidence that the Au coverage of the surface is less than 1 ML, suggest that the honeycomb configuration is more plausible than the CHCT one, which has been considered to be most suitable for the atomic structure of the commensurate region in the surface. [DOI: 10.1380/ejssnt.2004.146]
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  • Akihiro Fujii, Shu Kurokawa, Akira Sakai
    Type: Regular Paper
    Subject area: Nano-Science and -Technology
    Volume 2 (2004) Pages 155-159
    Released: April 23, 2004
    JOURNALS FREE ACCESS
    We studied high-bias conductance of Ag and Cu breaking nanocontacts and found that their transient conductance traces often exhibit a sudden conductance fluctuation and a subsequent rapid contact break, the same contact instability as we previously observed on Au nanocontacts [A. Fujii, et al., e-J. Surf. Sci. Nanotech. 2, 125 (2004)]. As in the case of Au, the conductance fluctuation tends to take place at a preferred threshold conductance Gth, which is found to increase in proportion to the contact current I. The slope of this straight I-Gth plot represents the critical current density jc for the onset of the conductance fluctuation. Our experimental results show that I-Gth plots of Ag and Cu are nearly the same as that of Au, suggesting similar jc values for three noble metal nanocontacts. [DOI:10.1380/ejssnt.2004.155]
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  • Fumio Shimokoshi, Iwao Matsuda, Shuji Hasegawa, Shozo Ino
    Type: Regular Paper
    Subject area: Structures
    Volume 2 (2004) Pages 178-185
    Released: June 30, 2004
    JOURNALS FREE ACCESS
    Surface superstructures induced by adsorptions of divalent atoms (Ca and Sr) on a Si(111) substrate were investigated by reflection-high-energy electron diffraction (RHEED). After depositing Ca or Sr of 1∼3 monolayers, followed by post heating at temperatures ranging from 400 °C to 900 °C, successive changes in structure were observed due to the coverage decrease by thermal desorption of the adsorbates; 1 × 1, √3 × √3, 2 × 1, 9 × 1, 7 × 1, 5 × 1, 3 × 1, and also complicated undefined superstructures were observed before returning to the clean 7 × 7 structure. While the observed changes were similar to each other between the Ca and Sr cases, there were differences. The 9 × 1 phase was clear for Sr adsorption, while the 7 × 1 was distinct for Ca case. For the Sr case, the superlattice spots of the adjacent phases were coexisted at the intermediate coverages, meaning that the domains of the two phases coexisted separately (phase separation). For Ca case, on the other hand, the superlattice spots continuously shifted in position to those of the next phase with decrease of Ca coverage. This phenomenon was well reproduced by a simple kinematical simulation of diffraction. For example, when the 5 × 1 and 3 × 1 superstructures are mixed microscopically with different ratios, a new superlattice spot appears between the fifth- and third-fractional order spots, and its position shifts depending on the area ratio. Such a microscopic phase mixture is consistent with the previous observations by scanning tunneling microscopy. [DOI: 10.1380/ejssnt.2004.178]
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  • Katsunori Tagami, Masaru Tsukada
    Type: Regular Paper
    Subject area: Nano-Science and -Technology
    Volume 2 (2004) Pages 186-190
    Released: July 08, 2004
    JOURNALS FREE ACCESS
    We investigated theoretically the effects of molecular rotation on the STM tunneling conductance for three types of σ-bonded molecules, i.e., (a) bicyclo[2,2,2]octylmethylthiolate (BCO), (b) cyclohexylmethylthiolate (cHex), and (c) 1-pentanethiolate (C5), which are anchored to the Au(111) surface by Au-S bond. In the case of BCO and cHex, the conductance does not change when the molecules transform from the most stable to metastable configurations. In contrast, in the case of C5, the conductance is found to decrease markedly, which means that transformation from the all- trans to gauche conformation can work as a switch between ON and OFF states. This finding would give a possible mechanism of the conductance switching recently observed in the STM images for the C5 molecules inserted into the BCO SAM matrix. [DOI: 10.1380/ejssnt.2004.186]
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  • Katsunori Tagami, Masaru Tsukada
    Type: Regular Paper
    Subject area: Nano-Science and -Technology
    Volume 2 (2004) Pages 205-209
    Released: September 08, 2004
    JOURNALS FREE ACCESS
    By theoretical simulations the relationship between the quantum transport current and magnetic field induced current in triangular nanographene molecules is investigated. In both cases the time-reversal symmetry between the doubly degenerate states of the isolated molecule is broken, which results in incomplete cancellation of the two equivalent circulating current patterns with opposite flow directions. This shows that the source-drain driven current loop and the diamagnetic circulating current can be understood on the same theoretical footing. [DOI: 10.1380/ejssnt.2004.205]
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  • Muneyuki Tsuda, Wilson Agerico Diño, Hiroshi Nakanishi, Hideaki ...
    Type: Regular Paper
    Subject area: Catalysis
    Volume 2 (2004) Pages 226-229
    Released: October 23, 2004
    JOURNALS FREE ACCESS
    We consider hemoglobin (Hb) components for possible use as cathode electrode catalyst in polymer electrolyte fuel cells (PEFCs). We choose iron-porphyrin (FeP) and (imidazole)FeP [(Im)FeP] as a representative heme complex of the Hb active site, and investigate their catalytic activities for O2 dissociation using it ab initio calculations based on density functional theory (DFT). The imidazole ligand suppresses the donation/back-donation of electrons between Fe and O2, resulting in the weakening of the Fe-O2 bond and the strengthening of the O-O bond. Therefore, the catalytic activity of FeP is higher than that of (Im)FeP. [DOI: 10.1380/ejssnt.2004.226]
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Superexpress Letters
  • Wilson Agerico Diño, Hiroshi Nakanishi, Hideaki Kasai, Tsuyoshi ...
    Type: Superexpress Letter
    Subject area: Interdisciplinary
    Volume 2 (2004) Pages 77-80
    Released: February 10, 2004
    JOURNALS FREE ACCESS
    Based on the density functional theory, we investigate and discuss how hydrogen behaves at the edges of graphite sheets/layers, in particular the zigzag edge. Our calculation results show that the zigzag edge is very reactive. It is possible to dissociatively adsorb H2 on these surfaces without any activation barrier hindering the reaction. To be able to use carbon nanomaterials as a means to store hydrogen, one of the crucial factors necessary would be the ability to dissociate hydrogen first, and then (somehow) induce them to stick to the carbons on each sheets. The results we present here suggest the possible utility of the zigzag edge as a reaction channel to carry out the aforementioned process. [DOI: 10.1380/ejssnt.2004.77]
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  • Muneyuki Tsuda, Wilson Agerico Diño, Susumu Watanabe, Hiroshi N ...
    Type: Superexpress Letter
    Subject area: Catalysis
    Volume 2 (2004) Pages 200-204
    Released: September 04, 2004
    JOURNALS FREE ACCESS
    We investigate and discuss spin polarization effects on cyclohexane (C6H12) dehydrogenation with a Ni atom, by performing total energy calculations based on the density functional theory (DFT). We consider the process where cyclohexane approaches the Ni atom, and determine the reaction paths from the calculated potential energy surfaces (PESs) for singlet and triplet systems. The C-H bond dissociation processes of the cyclohexane for both singlet and triplet systems are almost the same. After interacting with the Ni atom, the Ni atom draws an H atom from the cyclohexane, and an H-Ni bond is formed. With the C-H bond broken, cyclohexyl intermediate (C6H11) separates from the Ni atom. For the triplet system, however, no energy is required to separate the cyclohexyl from the H-Ni system due to the repulsion between up-spin electrons, resulting from the up-spin electron transfer from the Ni atom to the C atom. Therefore, it indicates that the magnetic properties of the Ni atom are favorable for the cyclohexane dehydrogenation. [DOI: 10.1380/ejssnt.2004.200]
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  • Fumihiko Yamada, Yutaka Sacho, Takuya Matsumoto, Hidekazu Tanaka, Tomo ...
    Type: Superexpress Letter
    Subject area: Nano-Science and -Technology
    Volume 2 (2004) Pages 222-225
    Released: October 20, 2004
    JOURNALS FREE ACCESS
    We demonstrated DNA-template assembly of gold-nanoparticles AuNP via step-by-step binding reaction. The control of hydrophilicity for mica surface makes it possible to preserve the structure of AuNP-binded DNA network with resistance to Au-thiolate reaction in ethanol solvent. This method realizes the formation of a continuous AuNP array with uniform height and small width. [DOI: 10.1380/ejssnt.2004.222]
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Conference -ALC'03-
  • Maya Kiskinova
    Type: Conference -ALC'03-
    Subject area: Electronic Properties
    Volume 2 (2004) Pages 1-7
    Released: January 19, 2004
    JOURNALS FREE ACCESS
    The paper is a brief overview of the potential of the photoemission microscopy methods emphasizing on some recent achievements of chemical imaging and spectromicroscopy in identification of sub-micron area chemical phases developed as a result of surface reactions, propagating reaction fronts and mass transport due to thermal and/or electromigration. [DOI: 10.1380/ejssnt.2004.1]
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  • Yoshiyuki Hisada, Yoshihito Mitsuoka, Shinichi Mukainakano, Hidetoshi ...
    Type: Conference-ALC'03-
    Subject area: Structures
    Volume 2 (2004) Pages 8-16
    Released: January 22, 2004
    JOURNALS FREE ACCESS
    Graphitized 4H-SiC(0001) Si- and (000-1)C-terminated surfaces with an offset angle of 8° in the ultra high vacuum (UHV) are observed by scanning tunneling microscopy (STM) and reflection high-energy electron diffraction (RHEED). A network of string-shaped structures is developed on the Si-terminated surface after annealed at 1800°C. On the other hand, many protrusions corresponding to the ends of carbon nanotubes are generated on the C-terminated surface at the temperature. The network developed on the Si-terminated surface is composed of string-shaped structures along and perpendicular to step edges. The development of the network on the Si-terminated surface is investigated. It is found that string-shaped structures along step edges are generated at 1400°C, followed by the generation of that perpendicular to step edges at 1700°C. Models for the generation of string-shaped structures along and perpendicular to step edges are proposed. [DOI: 10.1380/ejssnt.2004.8]
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  • Akira Tonomura
    Type: Conference -ALC'03-
    Subject area: Instrumentations and Techniques
    Volume 2 (2004) Pages 17-23
    Released: January 29, 2004
    JOURNALS FREE ACCESS
    With our newly developed 1-MV field emission electron microscope, which has the brightest electron beam and the highest lattice resolution, we obtained new results about unconventional behaviors of quantized vortices in high-Tc superconductors. Although vortices have hitherto been observed only at the superconductor surfaces by conventional methods such as Bitter method, vortices inside high-Tc superconductors became observable by Lorentz microscopy using our 1-MV microscope. Making full use of this technique, we found various behaviors of vortices peculiar to high-Tc superconductors. [DOI: 10.1380/ejssnt.2004.17]
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  • Hyung-Ik Lee, Dae Won Moon, Suhk Kun Oh, Hee Jae Kang, Hyun Kyong Kim, ...
    Type: Conference -ALC'03-
    Subject area: Instruments and Techniques
    Volume 2 (2004) Pages 24-27
    Released: January 29, 2004
    JOURNALS FREE ACCESS
    The sputter damage profile of a Si(100) by low energy O2+ and Ar+ ion bombardment with various incident angles was measured by using medium energy ion scattering spectroscopy. It was observed that the damaged Si surface layer could be minimized down to 0.5∼0.6 nm with grazing incident angle of 80° for 500 eV Ar+ and O2+ ion bombardment. The SIMS depth resolution for a GaAs delta layer in Si and a multiple boron nitride delta layer in Si with low O2+ ion bombardment was sub-nm, which is in a good agreement with the measured damaged layer thickness. [DOI: 10.1380/ejssnt.2004.24]
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  • Tetsuo Sakamoto, Kazuaki Shibata, Kazunari Takanashi, Masanori Owari, ...
    Type: Conference -ALC'03-
    Subject area: Environmental and Energy Technology
    Volume 2 (2004) Pages 45-51
    Released: February 10, 2004
    JOURNALS FREE ACCESS
    A time-of-flight secondary ion mass spectrometry (TOF-SIMS) with a feature of in situ micro-cross-sectioning of samples was applied to coal fly ash particles. The apparatus is equipped with two gallium focused ion beams (Ga-FIBs); one is used for micro-cross-sectioning of a particle to expose an analyzing area at aimed part, and the other is pulsed for TOF-SIMS analysis. By using this apparatus coal fly ash particle surfaces and interiors were analyzed. Hollow and solid particles were found and their internal structures were revealed with secondary electron imaging and mass spectrometric measurements. The main constituents were Al and Si with minor ones of Na, Mg, K, Ti and Fe. As for the hollow particle, it was found a difference in both inorganic and organic constituents between its outer and inner surface. On the surface, Na, Mg, Ca, Cl, and also organic compounds were enriched. Solid particle had a uniform inorganic composition over its surface and interior. [DOI: 10.1380/ejssnt.2004.45]
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  • Hannes Lichte
    Type: Conference -ALC'03-
    Subject area: Instruments and Techniques
    Volume 2 (2004) Pages 52-55
    Released: February 10, 2004
    JOURNALS FREE ACCESS
    In 1953, Gottfried Moellenstedt invented the electron biprism, more or less by accident, with the serendipity characteristic to him: Aiming at dark-field imaging in an electron microscope, he stretched a thin tungsten wire across the objective aperture to block off the zero beam. However, instead of a dark field image, because of inadvertent charging of the wire under the beam, he found two images of the ZnO-needles serving as an object. Instead of trying the dark field imaging over and over again, he asked what the effect would be if the obtained two images were superimposed. Is coherence given? Moellenstedt, educated by Walther Kossel in diffraction of electron waves, had a vision: Together with his PhD-student Heinrich Dueker, he developed the electron biprism, consisting of a 1 micron m thin wire deliberately chargeable by means of a voltage source, as a beam splitter for coherent superposition of the electron waves passing the filament on the right and on the left. In 1955 they published the first results showing biprism interference fringes [G. Moellenstedt and H. Dueker, Naturwiss. 42, 41 (1955)], which, since then, gave access to the understanding of electron waves and their use for analysis of object structures up to atomic dimensions. [DOI: 10.1380/ejssnt.2004.52]
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  • David C. Joy, Bernhard G. Frost
    Type: Conference -ALC'03-
    Subject area: Instruments and Techniques
    Volume 2 (2004) Pages 81-88
    Released: February 16, 2004
    JOURNALS FREE ACCESS
    We have designed a low voltage point source microscope operated with a nanotip field emitter and without any electron optical lenses such that it can be operated in the transmission mode as well as in a reflection mode. An electron gun needed in the reflection mode is the most important difference between the two modes of operation. The magnification of the object wave is achieved by placing the specimen in the divergent electron beam of a nanotip field emitter and observing the object wave using a micro channel plate (MCP) at a great distance from the sample. As no lenses are present a procedure for scaling the magnification has been developed. Since electrons from a point source are highly coherent the out of focus images of the sample are interferograms and contain true three dimensional information of the sample. The transmission mode gives us the following results: (1) Electrons diffracted at an edge of the specimen cause Fresnel fringes in the image plane. (2) An electrically charged holey carbon foil can act in the same way on the electrons as the Young's double slit experiment and results in an interference pattern consisting of parallel fringes. The reflection mode shows us: (1) The image depends on the angle of reflection. (2) An arrangement similar to a field ion microscope resolves single atoms of the specimen. [DOI: 10.1380/ejssnt.2004.81]
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  • I. L. Bolotin, A. Kutana, B. N. Makarenko, J. W. Rabalais
    Type: Conference -ALC'03-
    Subject area: Instruments and Techniques
    Volume 2 (2004) Pages 93-98
    Released: February 24, 2004
    JOURNALS FREE ACCESS
    The technique of angle resolved mapping of scattering and recoiling imaging spectra (SARIS) combined with computer simulations is demonstrated to be a valuable tool for characterization of atomic collision events on surfaces. The energy distributions of scattered Kr and Ne and fast recoiled Pt and Ni atoms from Pt(111) and Ni(111) surfaces were measured as a function of exit angle. The use of a large area microchannel plate (MCP) detector and time-of-flight (TOF) techniques decreases the collection time and increases the number of detected trajectories above that of other designs. Classical ion trajectory simulations using the three-dimensional scattering and recoiling imaging code (SARIC) are used to simulate the kinematics of the scattering and recoiling particles. It is shown that SARIS mapping allows one to probe the kinematics of both scattered and recoiled particles, the probability for their occurrence in specific trajectories, and the atomic layers from which the particles originate. [DOI: 10.1380/ejssnt.2004.93]
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  • Gabor A. Somorjai, Keng C. Chou, Minchul Yang
    Type: Conference -ALC'03-
    Subject area: Instruments and Techniques
    Volume 2 (2004) Pages 106-118
    Released: February 28, 2004
    JOURNALS FREE ACCESS
    Sum frequency generation (SFG) vibrational spectroscopy is highly surface sensitive because the second-order nonlinear optical process is only allowed in media without inversion symmetry, such as interfaces. As an all-optical technique, SFG can be employed to study molecular compositions and structures at solid/liquid and at solid/high pressure gas interfaces. This paper discusses the applications of SFG in our laboratory to study the reaction intermediates of catalytic reactions on metal surfaces under high-pressure conditions, the surface composition and structure of polymers, and the interfacial properties of proteins on liquid/solid interfaces. [DOI: 10.1380/ejssnt.2004.106]
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  • Bernhard G. Frost, David C. Joy, Alex Thesen
    Type: Conference -ALC'03-
    Subject area: Devices and Sensors
    Volume 2 (2004) Pages 119-124
    Released: March 03, 2004
    JOURNALS FREE ACCESS
    We briefly discuss how to set-up our Hitachi HF-2000 transmission electron microscope for medium magnification holography. Then we apply this technique to examine the activation of an as-doped wafer by annealing. We also present voltage profiles of the source-drain region of a CMOS transistor with 75 nm gate architecture taken from an off-the-shelf Intel PIII processor. Special attention is given to the analysis of the reconstructed holograms. [DOI: 10.1380/ejssnt.2004.119]
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  • Akihiro Fujii, Jun-ichi Mizobata, Shu Kurokawa, Akira Sakai
    Type: Conference -ALC'03-
    Subject area: Nano-Science and -Technology
    Volume 2 (2004) Pages 125-130
    Released: March 05, 2004
    JOURNALS FREE ACCESS
    Conductance and its bias dependence have been measured on Au and Ag breaking nanocontacts for biases up to 3.0 V at room temperature in ultrahigh vacuum. Under high-bias/high-current conditions, both Au and Ag contacts often show a characteristic conductance fluctuation when the conductance attains a certain critical value Gth. This critical conductance ranges from about 10G0 to about 50G0 (G0 ≡ 2e2/h is the quantum unit of conductance) and increases with the bias. When Gth is plotted against the contact current I, we obtained a linear I-Gth plot for Au contacts. Since Gth is in a semiclassical regime and hence should be proportional to the cross sectional area of the contact, the slope of the I-Gth plot represents a critical current density for the onset of the conductance fluctuation. These observations indicate that the conductance fluctuation is due to certain current-induced contact instability. When the current density exceeds the critical value, a contact becomes unstable and tends to be ruptured, leaving small chances of further necking deformation down to a single-atom contact. [DOI: 10.1380/ejssnt.2004.125]
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  • M. Nojima, M. Toi, A. Maekawa, B. Tomiyasu, T. Sakamoto, M. Owari, Y. ...
    Type: Conference -ALC'03-
    Subject area: Instruments and Techniques
    Volume 2 (2004) Pages 131-135
    Released: March 09, 2004
    JOURNALS FREE ACCESS
    We have been developing the nano-beam secondary ion mass spectrometry (SIMS) apparatus, which can realize high spatial resolution and high efficiency of secondary ion detection. In this paper, the nano-beam SIMS method was introduced for the purpose of characterization for practical materials: contact holes. Contrasts of ion induced secondary electron (ISE) image and ion induced secondary ion (ISI) image were different. The difference was discussed with respect to information depth and chemical sensitivity. Elemental maps were obtained with nano-dimension and the maps provided many aspects of the sample. [DOI: 10.1380/ejssnt.2004.131]
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  • Karl-Heinz Ernst, Manfred Parschau, Roman Fasel
    Type: Conference -ALC'03-
    Subject area: Structures
    Volume 2 (2004) Pages 136-140
    Released: March 11, 2004
    JOURNALS FREE ACCESS
    Adsorption of the chiral hydrocarbon heptahelicene on Cu(111) has been investigated by means of low energy electron diffraction (LEED) and scanning tunneling microscopy (STM) at cryogenic temperatures. The pure enantiomers form extended chiral structures which are mirror images of each other and mirror domains are observed after adsorption of the racemic mixture. Although periodicity and orientation of the adsorbate lattices with respect to the substrate lattice are almost identical, as concluded from LEED, STM reveals different local structures for racemic mixture and pure enantiomers. This is explained by quasi-hexagonal two-dimensional packing in all structures but different relative azimuthal orientations of the molecules within the adsorbate lattice. [DOI: 10.1380/ejssnt.2004.136]
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Reviews
  • Victor G. Lifshits, Yury L. Gavrilyuk, Dmitry A. Tsukanov, Boris K. Ch ...
    Type: Review Paper
    Subject area: Nano-Science and -Technology
    Volume 2 (2004) Pages 56-76
    Released: February 10, 2004
    JOURNALS FREE ACCESS
    The general observations concerning the commonly accepted terms related to Si surface like 'surface', 'surface phase', 'adatoms', 'in phase' and 'on phase' atoms are given. Surface phases preparation, composition and their role in surface processes is examined. The influence of surface phases on processing as diffusion, desorption, codeposition, interface formation and surface conductivity is described. [DOI: 10.1380/ejssnt.2004.56]
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  • Yuji Okawa, Masakazu Aono
    Type: Review Paper
    Subject area: Nano-Science and -Technology
    Volume 2 (2004) Pages 99-105
    Released: February 25, 2004
    JOURNALS FREE ACCESS
    To realize novel nanodevices beyond today's silicon-based transistors, a method is needed that will allow us to create nanowires at designated positions. In this review article, we introduce our method for creating a conjugated polymer nanowire by initiating a chain polymerization of organic molecules using the tip of a scanning tunneling microscope. We have demonstrated this method using a self-ordered monomolecular layer of amphiphilic diacetylene compound adsorbed on a graphite surface. The termination of the chain polymerization can also be controlled by making an artificial defect in advance. [DOI: 10.1380/ejssnt.2004.99]
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  • Iwao Matsuda, Takehiro Tanikawa, Shuji Hasegawa, Han Woong Yeom, Kensu ...
    Type: Review Paper
    Subject area: Electronic Properties
    Volume 2 (2004) Pages 169-177
    Released: May 12, 2004
    JOURNALS FREE ACCESS
    A series of our studies are reviewed on quantized electronic states confined in thin metal films on semiconductor surfaces, investigated by scanning tunneling microscopy and angle-resolved photoemission spectroscopy. Atomically flat and epitaxial Ag(111) films of 5 - 30 atomic layer thick grew on Si(001)2 × 1 and Si(111)7 × 7 clean substrates by depositing Ag at about 100 K and subsequent annealing up to 300 - 450 K. Discrete Ag 5s states were observed at binding energies of 0.3 - 3 eV below Fermi level, whose energy positions depended on the film thickness, together with the thickness-independent surface state of Ag(111). The discrete electronic states are interpreted in terms of the quantum-well states (QWS) based on the phase-shift quantization rule. The phase shift, energy dispersion, and energy-versus-thickness relation (Structure Plot) of the QWS's were consistently derived. On the other hand, for the in-plane dispersion, in contrast to the expected free-electron-like behavior, the QWS's showed (i) a significant enhancement of the in-plane effective mass with decreasing binding energy, and (ii) a splitting of a QWS into two electronic states having different dispersions at off-Γ points. Such unexpected properties of the QWS were found obviously related to an interaction with the Si substrate band structure. The QWS splitting is explained by the energy dependence in reflection phase shift at the film-substrate interface occurring at the substrate band edge. [DOI: 10.1380/ejssnt.2004.169]
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  • Manabu Kiguchi, Koichiro Saiki
    Type: Review Paper
    Subject area: Electronic Properties
    Volume 2 (2004) Pages 191-199
    Released: July 23, 2004
    JOURNALS FREE ACCESS
    A series of our studies are reviewed on the atomic and electronic structures at well-defined alkali halide/metal interfaces. Alkali halides are found to grow heteroepitaxially on fcc metal (001) surfaces, that is, a well-defined insulator/metal interface can be prepared. The electronic structure at the interface is studied by near edge x-ray absorption fine structure (NEXAFS), x-ray photoemission spectroscopy and Auger electron spectroscopy. We can show a clear experimental evidence for the formation of metal induced gap states (MIGS), which originate not from chemical bonds at the interface, but from states formed by the proximity to a metal. The character of MIGS is studied by the polarization and thickness dependent NEXAFS. MIGS are states whose wave functions orient in the surface normal direction. The decay length of MIGS is about mono layer thickness, and it depends on rather an alkali halide than a metal. Finally, we discuss a possibility of the interface superconductivity. [DOI:10.1380/ejssnt.2004.191]
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  • Kazuyuki Sakamoto, R. I. G. Uhrberg
    Type: Review Paper
    Subject area: Electronic Properties
    Volume 2 (2004) Pages 210-221
    Released: October 05, 2004
    JOURNALS FREE ACCESS
    In this review, we present a series of photoemission studies performed on the so-called metal induced Si(111)-(3×1) surface, which is one of the most well known 1D structure formed on a Si(111) surface. Three different kinds of metals have been used as adsorbate, K, Ca, and Ag.On the K/Si(111)-(3×1) surface, five surface components were observed in the Si 2p core-level spectra. The energy shift and intensity of each surface component indicates that this surface has the honeycomb-chain-channel (HCC) structure with a K coverage of 1⁄3 ML. The extra spots observed in the LEED pattern of the so-called Ca/Si(111)-(3×1) surface suggest that this surface has a (3×2) periodicity instead of the (3×1) periodicity reported in the literature. By considering the energy shift and intensity of each Si 2p surface component, we conclude that the structure of the (3×2) phase is basically the same as that of the HCC model, but with a Ca coverage of 1⁄6 ML. Regarding the valence-band, five surface states, none of which crosses the Fermi level, were observed in the bulk band gap. The dispersion features of three of them agree well with those of monovalent atom adsorbed Si(111)-(3×1) surfaces along the chain direction. The two other states observed in the band gap have not been reported in the literature, and they are interpreted as surface states that are peculiar to the Ca/Si(111)-(3×2) surface due to the 1⁄6 ML coverage. Regarding the Ag/Si(111) surface, a new c(12×2) phase is observed in LEED after cooling the room temperature (6×1) phase to 70 K. In the Si 2p core-level spectra and in the valence band spectra, no significant difference is observed between the two surfaces. Further, the origins of the Si 2p surface components and the surface states of these surfaces are well explained using the HCC model. These results indicate that the basic structure of this Ag/Si(111) surface is quite similar with the HCC model but with a c(12×2) periodicity, and that the (6×1) structure results from thermal vibrations of the surface atoms. [DOI: 10.1380/ejssnt.2004.210]
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  • Mitsuhiro Katayama, Shin-ichi Honda, Takashi Ikuno, Kuei-Yi Lee, Masar ...
    Type: Review Paper
    Subject area: Nano-Science and -Technology
    Volume 2 (2004) Pages 244-255
    Released: December 24, 2004
    JOURNALS FREE ACCESS
    In this review, we demonstrate the device-oriented synthesis of carbon nanotubes (CNTs), by taking an energy storage device and a field electron emitter as examples. As one of the most desirable approaches to fabricating nanostructured hybrids between carbon nanotubes and inorganic materials, we present a method of coating carbon nanotubes with inorganic materials in multishell form, and its application to nanoprobe fabrication. [DOI: 10.1380/ejssnt.2004.244]
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Conference -IWSI-
  • Yasuhiko Terada, Byoung-Ki Choi, Seiji Heike, Masaaki Fujimori, Tomihi ...
    Type: Conference -IWSI-
    Subject area: Nano-Science and -Technology
    Volume 2 (2004) Pages 28-31
    Released: February 04, 2004
    JOURNALS FREE ACCESS
    We demonstrated fixing of conducting polymers onto hydrogen-terminated Si(100) surfaces via a pulse valve. The pulse-injected molecules were multiwalled carbon-nanotube, π-conjugated poly(3-hexlthiophene-2,5-diyl), poly(N-tert-butoxycarbonyl diphenylamine-4,4'-diyl), and poly((3-hexylthiophene-2,5-diyl)-co-(diphenyldisulfide-4,4'-diyl)). Each sample was dispersed or dissolved in a certain solvent before pulse injection. In all cases, the isolated molecules were observed by scanning tunneling microscopy. The results indicate that the pulse injection method can be used for fixing and isolating various conducting polymers. [DOI: 10.1380/ejssnt.2004.28]
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  • Yuji Suwa, Ryotaro Arita, Kazuhiko Kuroki, Hideo Aoki
    Type: Conference -IWSI-
    Subject area: Nano-Science and -Technology
    Volume 2 (2004) Pages 38-44
    Released: February 08, 2004
    JOURNALS FREE ACCESS
    We have designed organic polymers consisting of five-membered rings with first principles calculations to realize flat-band ferromagnetism. We describe how we can fulfill the condition for the ferromagnetism in polymers by attaching appropriate functional groups to the five-membered rings. We further discuss how our original proposal [Arita et al., Phys. Rev. Lett. 88, 127202 (2002)] for the best candidate (polyaminotriazole) may even be improved by its chemical derivative. [DOI: 10.1380/ejssnt.2004.38]
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  • Atsushi Taninaka, Haruhito Kato, Kazuhiro Shino, Toshiki Sugai, Yasuhi ...
    Type: Conference -IWSI-
    Subject area: Nano-Materials
    Volume 2 (2004) Pages 89-92
    Released: February 17, 2004
    JOURNALS FREE ACCESS
    We have investigated monolayer and multilayer islands of La2@C80, La@C82 and La2@C72 grown on a hydrogen-terminated Si(100)-2×1 surface by ultra-high-vacuum scanning tunneling microscopy/spectroscopy. The observed La2@C80 molecule has a spherical shape, consistent with a recent result by synchrotron X-ray measurements. The La2@C72 molecules are observed by STM as ellipsoids, consistent with a recent report by the 13C-NMR structural analysis. The energy gap for the La2@C80 multilayer islands is measured to be 1.3-1.5 eV, whereas that for La@C82 is 0.5 eV, indicating that the Ih cage of the La2@C80 molecule is highly stabilized by an electron transfer from the encaged La atoms. The energy gap of the La2@C72 multi-layer islands is measured by STS as 1.0-1.2 eV, suggesting that the C72 carbon cage is stabilized by a localized electron transfer from the encaged La atoms to the fused-pentagon area of the fullerene cage. [DOI: 10.1380/ejssnt.2004.89]
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  • Emiko Ishikawa, Ryo Shoda, Nahoko Matsuura, Masanori Ono, Toyoaki Eguc ...
    Type: Conference -IWSI-
    Subject area: Instruments and Techniques
    Volume 2 (2004) Pages 151-154
    Released: April 14, 2004
    JOURNALS FREE ACCESS
    An ultralow temperature scanning tunneling microscope (STM) was developed by installing an STM head in a dilution refrigerator. Using the apparatus, STM images and the differential tunneling conductance spectra were taken at the sample temperature of 90 mK on a cleaved surface of 2H-NbSe2. The atomically-resolved and the CDW-modulated STM images, and the superconduting gap as well as the CDW gap in the tunneling conduction (dI/dV) spectra were observed. [DOI: 10.1380/ejssnt.2004.151]
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  • Masaaki Fujimori, Seiji Heike, Yasuhiko Terada, Tomihiro Hashizume
    Type: Conference -IWSI-
    Subject area: Nano-Science and -Technology
    Volume 2 (2004) Pages 160-164
    Released: April 29, 2004
    JOURNALS FREE ACCESS
    A fabrication method of four-probe fine electrodes on a Si(100)-2×1-H surface was developed. The method involves conventional lithographic and scanning-probe nano-fabrication techniques followed by a high-temperature cleaning process of the surface. Using scanning tunneling microscopy, it was confirmed that a Si(100)-2×1-H surface was formed except for the fine electrode areas. Tunneling spectroscopy showed that the metallic feature remains on the electrode after the high-temperature cleaning process. To examine function of the electrodes, electrical transport measurements of a nanoscale silver wire were performed. The result exhibited significant conductance of the wire. From these results, it was concluded that the fabricated fine electrodes have the ability to measure electrical conduction of nanostructures fabricated on surfaces. [DOI: 10.1380/ejssnt.2004.160]
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  • Masanori Ono, Takahiro Nishio, Toyoaki Eguchi, Yukio Hasegawa
    Type: Conference -IWSI-
    Subject area: Micro- and Nano-Fabrication
    Volume 2 (2004) Pages 165-168
    Released: April 29, 2004
    JOURNALS FREE ACCESS
    Using a low-temperature scanning tunneling microscope, atom manipulations were performed on Cu(111) surface. We succeeded in manipulating single Cu atoms which were deposited on the Cu substrate at low temperature, and arranging them in an intended pattern. Besides the brightly contrasted Cu adatom, we also successfully moved single dark spots, presumably an adsorbed molecule of carbon monoxide, by using the same manipulation technique. [DOI:10.1380/ejssnt.2004.165]
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Conference -JRSSS6-
  • Z. An, M. Hirai, M. Kusaka, M. Iwami
    Type: Conference -JRSSS6-
    Subject area: Thin Films
    Volume 2 (2004) Pages 230-233
    Released: December 07, 2004
    JOURNALS FREE ACCESS
    PEEM (photoemission electron microscopy), AES (Auger electron spectroscopy) and SXES (soft X-ray emission spectroscopy) studies have been carried out on Cu(thin film)/3C-SiC(substrate) contact systems. The PEEM studies have clarified both lateral diffusion and microstructure formation on the Cu/3C-SiC specimen surfaces due to heat treatment. The AES has shown accumulation of carbon atoms on top of the specimen surface at high temperature annealing. The SXES studies have elucidated a silicide, i.e., Cu3Si, formation for the heat treated Cu(film)/3C-SiC specimen. A structural model is proposed for the heat treated Cu(30 nm)/3C-SiC(substrate) specimen. [DOI: 10.1380/ejssnt.2004.230]
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  • B. V. Andryushechkin, K. N. Eltsov, V. M. Shevlyuga
    Type: Conference -JRSSS6-
    Subject area: Structures
    Volume 2 (2004) Pages 234-240
    Released: December 17, 2004
    JOURNALS FREE ACCESS
    Halide nucleation and growth on monocrystalline copper substrates under molecular halogens action was studied by means of Auger Electron Spectroscopy (AES) and Scanning Tunnelling Microscopy (STM). It was found that copper iodide grows on Cu(100) and Cu(111) in a layer-by-layer mode with its outer hexagonal plane parallel to the substrate surface. The STM images of copper iodide demonstrate Moiré-like superstructures. The nature of these superstructures is explained in terms of superposition of the copper iodide layer and the underlying interface monolayer. It was found that the interface layer preserves geometrical and electronic structure of the saturated chemisorbed iodine monolayer for both copper planes. Moreover, we have found out that orientation of copper iodide nuclei on a surface strongly depends on the step edges orientation, which, in turn, is determined by the direction of close-packed atomic rows in the saturated iodine monolayer. [DOI: 10.1380/ejssnt.2004.234]
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  • S. Q. Zheng, M.M. Rahman, M. Kawashima, M. Mori, T. Tambo, C. Tatsuyam ...
    Type: Conference -JRSSS6-
    Subject area: Thin Films
    Volume 2 (2004) Pages 256-260
    Released: December 24, 2004
    JOURNALS FREE ACCESS
    The Si1-xGex(x ≈ 0.25) films were grown on Si(001) substrate using ultra-thin amorphous Si(UTA-Si) buffer layers with thickness from 0∼30 Å by molecular beam epitaxy. The films were mainly characterized by a reciprocal space mapping performed on a high-resolution X-ray diffraction. It is shown that the smooth and relaxed SiGe alloy layers are obtained using UTA-Si buffer layers, without the necessity of using several microns of thick compositionally graded layers. The surface morphology and crystal quality of SiGe thin film can be improved obviously. The strains in both [001] and [110] directions were relaxed greatly depending on the thickness of UTA-Si. [DOI: 10.1380/ejssnt.2004.256]
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Conference -Nano-org. & Func.-
  • Shouichi Sakakihara, Hiroyuki Noji
    Type: Conference -Nano-org. & Func.-
    Subject area: Bio-Science and -Technology
    Volume 2 (2004) Pages 241-243
    Released: December 21, 2004
    JOURNALS FREE ACCESS
    F1-ATPase, which is a part of ATP synthase, catalyzes the hydrolysis of ATP by itself. F1-ATPase is a single-molecule motor driven by the energy liberated from ATP hydrolysis. This rotation have been confirmed by a single-molecule rotation assay. By use of magnetic beads as the probe of microscopic image, the rotation of F1-ATPase have been controlled by an electromagnetic system. It is expected that if the ATP-binding of F1 triggers the rotation, the affinity of ATP-binding changes with the rotation angle. This feature was studied experimentally using the electromagnetic system. [DOI: 10.1380/ejssnt.2004.241]
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