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排序方式: 共有664条查询结果,搜索用时 15 毫秒
1.
Yahachi Saito Tadao Koyama Kenichiro Kawabata 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1997,40(1):421-424
Single-layer (SL) carbon tubes were produced by arc evaporation of graphite rods containing iron-group metals (Fe, Co, Ni, Fe/Co, Co/Ni, Fe/Ni) under He and Ar gas. Transmission electron microscopy (TEM) revealed that these elemental and binary metals, excluding Fe which need a special atmosphere (a mixture of Ar and CH4), showed catalytic activity producing SL tubes under pure inactive gases. Fe/Ni alloy was the most effectual catalysts for producing SL tubes. The highest abundance of SL tubes in raw soot was estimated to be ~ 10% from TEM observation. Smoke particles directly caught on TEM grids near an evaporation source during arcburning were also investigated, and it was suggested that small metal particles were first formed in the gas phase and then SL tubes grew from them. 相似文献
2.
Mengxing Cui Ryuichi Murase Yongbing Shen Tetsu Sato Shohei Koyama Kaiji Uchida Tappei Tanabe Shinya Takaishi Masahiro Yamashita Hiroaki Iguchi 《Chemical science》2022,13(17):4902
Electrical conduction among metallocycles has been unexplored because of the difficulty in creating electronic transport pathways. In this work, we present an electrocrystallization strategy for synthesizing an intrinsically electron-conductive metallocycle, [Ni6(NDI-Hpz)6(dma)12(NO3)6]·5DMA·nH2O (PMC-hexagon) (NDI-Hpz = N,N′-di(1H-pyrazol-4-yl)-1,4,5,8-naphthalenetetracarboxdiimide). The hexagonal metallocycle units are assembled into a densely packed ABCABC… sequence (like the fcc geometry) to construct one-dimensional (1D) helical π-stacked columns and 1D pore channels, which were maintained under the liberation of H2O molecules. The NDI cores were partially reduced to form radicals as charge carriers, resulting in a room-temperature conductivity of (1.2–2.1) × 10−4 S cm−1 (pressed pellet), which is superior to that of most NDI-based conductors including metal–organic frameworks and organic crystals. These findings open up the use of metallocycles as building blocks for fabricating conductive porous molecular materials.Intrinsically electron-conductive metallocycle was synthesized. π-Radicals play a key role in constructing π-stacked columns among molecular hexagons and achieving high electrical conductivity over 10−4 S cm−1 in polycrystalline pellet. 相似文献
3.
Tasuku Onodera Yusuke Morita Michihisa Koyama Nozomu Hatakeyama Hiromitsu Takaba Momoji Kubo Jean-Michel Martin 《Applied Surface Science》2009,256(4):976-979
We investigated the influence of a nanometer scale film structure of a tribofilm generated from zinc dialkyldithiophosphate (ZDDP) anti-wear additive on its mechanical properties using a combined molecular dynamics (MD) and finite element (FE) method. The frictional behavior of an interface between a native iron oxide layer on steel surface and zinc metaphosphate - regarded as a model material of ZDDP tribofilm - was firstly studied using the MD method. The results showed that the iron atoms in the oxide layer diffused into the phosphate layer during the friction process. The zinc atoms in the phosphate layer also diffused into the oxide layer. Significant interdiffusion of iron and zinc atoms was observed with increasing simulation time. Thus, metallic phosphate with a gradient composition of iron and zinc atoms was formed on the phosphate/oxide interface. We then constructed an axisymmetric nanoindentation simulation model from the MD-derived structures at a certain simulation time and carried out a FE calculation. As a result, we found that the rubbed ZDDP tribofilm, including the phosphate with the gradient composition of metallic atoms, showed larger contact stiffness and hardness. The combined MD/FE simulation indicates that the tribofilm becomes stiffer and harder due to the interdiffusion of iron and zinc atoms on the tribofilm/oxide interface. We have found that the gradient composition formation in ZDDP tribofilm during friction process influences on its mechanical properties. 相似文献
4.
Musubu Ichikawa Nobuyasu Hiramatsu Norimasa Yokoyama Tetsuzo Miki Susumu Narita Toshiki Koyama Yoshio Taniguchi 《固体物理学:研究快报》2007,1(1):R37-R39
We demonstrate that a bipyridyl substituted oxadiazole (Bpy‐OXD) shows high electron mobility that reached above 10–3 cm2/Vs. We believe that the high mobility results from both the hybrid molecular structure of the two electron‐accepting units: bipyridyl and oxadiazole, and the planar molecular structure based on its lack of sterically hindered bulky substituent. The computational analysis elucidates that the amorphous nature of Bpy‐OXD in thin‐film state probably results from the polymorphic effect in isolated state and the volume effect in solid state. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
5.
Partially oxidized free-standing porous silicon films show a strongly superlinear increase in photoluminescence (PL) intensity above a threshold cw excitation intensity of 10 W/cm2. The PL-intensity increase can be expressed by a power law with n9 as a function of the excitation intensity. The PL-peak wavelength of this emission is slightly redshifted from that at low-excitation levels. These changes are fully reversible and reproducible, but not observed in samples on substrate. We attribute this behavior to thermal reexcitation of carriers trapped at the dangling bond states in initially nonluminescent Si nanocrystallites. 相似文献
6.
Optical near-field plasmon-enhancement techniques have made marked contributions to the field of subwavelength optical beam
spot generation for photonic devices. However, the metal material used is not sufficiently heat resistant for high-temperature
operating requirements, such as laser-assisted magnetic recording storage. Therefore, it is preferable to use a dielectric
material as a heat source for this application. To realize a subwavelength optical beam spot size using a dielectric material,
we extensively analyze a leaky mode dielectric waveguide with a thin core. Finally, we show a new ridge-type dielectric waveguide
using a leaky mode operation for a subwavelength beam spot. 相似文献
7.
8.
A new class of holography is proposed, in which (1) the evanescent part of a guided wave, or (2) the guided wave in a thin-film hologram is utilized as the reference wave and/or the illuminating one. The hologram was designated as “wave-guide hologram” and has advantages in the possibility of integration, wide field of view, and compactness and high reliability of the reconstructing system. The possibility of the waveguide hologram has been proved through reconstruction experiments with a guided wave of a waveguide hologram recorded with a plane reference wave. 相似文献
9.
“Laser-assisted magnetic recording”, in which a recording media is heated by a laser beam while writing data, is attracting
attention as a technology that enables a recording density of 1 Tb/in.2. There exists another technology for media in which the recording layer is constructed with many small projections that enable
high magnetic coercivity. This is called “patterned media”. For developing hard disk drives using these methods, we developed
a simulator that analyzes the optical intensity distribution from the optical head for laser-assisted recording and the temperature
profile on the patterned media. The simulator calculates the optical model using the finite-difference time-domain (FDTD)
method. The thermal analysis of the three-dimensional model allows fast calculations using the alternating direction implicit
(ADI) method. The heat source distribution data for thermal analysis is calculated in order to use the results of optical
analysis. The optical and thermal analyses of the laser-assisted recording model were investigated with the simulator. 相似文献
10.
Yoshitaka Koyama 《Communications in Mathematical Physics》1994,164(2):277-291
In this paper we give an explicit formula for level 1 vertex operators related to
as operators on the Fock spaces. We derive also their commutation relations. As an application we calculate with the vector representation of
, thereby extending the recent work on the staggered polarization of the XXZ-model. 相似文献