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91.
O. Tonomura Y. Mera A. Hida Y. Nakamura T. Meguro K. Maeda 《Applied Physics A: Materials Science & Processing》2002,74(2):311-316
It was found that STM (scanning tunneling microscopy) images of defects in highly oriented pyrolytic graphite introduced by
bombardment of 400 eV Ar+ ions in ultra-high vacuum exhibit substantial changes in the course of STM probing. Detailed examination of abrupt changes
in the tunneling current measured at defect sites during voltage scans shows that the primary cause of the defect-image change
was found to be neither the injected current nor the injected power but the absolute value of the voltage applied between
the probe tip and the sample. We propose that an electric polarization induced force attracting the sample surface toward
the probe tip widens the layer spacing of the graphite surface, leading to an acceleration of the lateral diffusion of interstitial
atoms introduced by the ion irradiation, which results in a change in the defect structures and the accompanying electronic
structures sensible in the STMimaging.
Received: 14 June 2001 / Accepted: 7 September 2001 / Published online: 20 December 2001 相似文献
92.
The impact of disorder introduced by intentional and unintentional (environmental) dopants on the charge transport has been investigated in boron‐ and nitrogen‐doped single‐walled carbon nanotubes, and in low‐mobility monolayer graphene. For doped single‐walled nanotubes a theoretically not predicted plateau‐like region and onsets of oscillatory behaviour in the conductance for boron‐ and nitrogen‐doped nanotubes were observed, respectively. The oscillatory behaviour suggests interplay between the dopants and the helical movement of charges along the tube due to the magnetic field. For low‐mobility graphene the simultaneous appearance of the filling‐factor 2 and 3 plateau was observed in the Quantum‐Hall regime. This is attributed to an electron‐spin–isospin interaction mediated through the high disorder. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
93.
T. Roman W. A. Diño H. Nakanishi H. Kasai 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(1):117-120
We investigate and discuss the adsorption of a few amino acids on (3,3)
carbon nanotubes and on graphite sheets through calculations within density functional theory. Results show weak binding of
the biomolecules on both substrates, but through generally favourable adsorption pathways. Zwitterion adsorption through the
charged amine and carboxylate groups are bound stronger to the nanotube surface in comparison to their nonionic counterparts,
as well as on histidine, phenylalanine, and cysteine side chain groups fixed in specific orientations. Binding strengths on
graphite suggest dissimilar trends for amino acid interactions with increasing
nanotube diameter. 相似文献
94.
Carbon fibers were deposited by laser-assisted chemical vapor (LCVD) deposition from ethylene at sub-atmospheric pressure. Prior Raman spectroscopy analysis allowed the determination of the crystal size (average value of 3 nm in the edge region and from 8 to 113 nm in the center region). In this analysis, the microstructure of as-grown and heat treated fibers was examined using micro-Raman spectroscopy and transmission electron microscopy. The analysis revealed the degree of three-dimensional ordering of graphite planes and that the fibers were porous. 相似文献
95.
The conductivity of nitrogen incorporated tetrahedral amorphous carbon (taC:N) films prepared by filtered cathodic vacuum arc (FCVA) system was studied. The film resistivity varied as a function of nitrogen content in a wide nitrogen content range from 1 to 23 at.%. An interesting phenomenon of the photoconductivity for the films was found, that the resistivity of those films with low nitrogen content (<5 at.%) increased due to the light irradiation. This kind of behavior of photoconductivity had not been discussed in previous papers on taC:N films. 相似文献
96.
Reza Rasuli 《Applied Surface Science》2010,256(24):7596-7599
A density functional theory (DFT) study of graphene synthesis from graphite oxidation and exfoliation is presented. The calculated DFT results for O adsorption predict CO as a most stable bond on the graphene oxide (GO) sheet. The obtained exfoliation energy for the graphene and the GO are 143 and ∼70 mJ/m2 that verify easier exfoliation of the graphite oxide compared with the graphite. Furthermore, the DFT results show that for decreasing the exfoliation energy of the GO at least two layers of the graphite should be oxidized during the oxidation process. 相似文献
97.
Susumu Takabayashi Keishi Okamoto Kunihiko Motomitsu Tatsuyuki Nakatani Hitoshi Suzuki 《Applied Surface Science》2008,254(9):2666-2670
A new method to calibrate the binding energy (EB) using Au nanocolloids as a calibrant in XPS analysis of diamondlike carbon (DLC) is proposed by considering the DLC films with different electrical resistivities. A few microliters of a dilute aqueous solution containing Au nanocolloids were dropped onto a small local surface area of the DLC film, which became a stain before XPS measurements by gradually drying in vacuo. The observed peak EB of the C 1s spectrum at another native surface (an area without Au nanocolloids) of the DLC film was calibrated by setting that of the Au 4f7/2 spectrum of the Au nanocolloids to 84.0 (83.98 ± 0.02) eV. The adequacy of this method was investigated by considering the correlation among the full width at half maximums (FWHMs) of the Au 4f7/2 spectra of the Au nanocolloids on the DLC surfaces and that of a Au plate as a reference. Consequently, the FWHM of the Au 4f7/2 spectrum of the Au nanocolloids on the DLC surface is a candidate to investigate the differential charging effect of the DLC surface, and the calibration method is reliable if the FWHM agrees with that of the Au plate. 相似文献
98.
The electronic (quantum) transport in a NG/FB/FG tunnel junction (where NG, FB and FG are a normal graphene layer, a ferromagnetic barrier connected to a gate and a ferromagnetic graphene layer, respectively) is investigated. The motions of the electrons in the graphene layers are taken to be governed by the Dirac Equation. Parallel (P) and antiparallel alignment (AP) of the magnetizations in the barrier and in the ferromagnetic graphene are considered. Our work focuses on the oscillation of the electrical conductance (Gq), of the spin conductance (Gs) and of the tunneling magneto resistance (TMR) of this magnetic tunnel junction. We find that, the quantum modulation due to the effect of the exchange field in FB will be seen in the plots the conductance and of the TMR as functions of the thickness of ferromagnetic barrier (L). The period of two multiplied sinusoidal terms of the modulation are seen to be controlled by varying the gate potential and the exchange field of the FB layer. The phenomenon, a quantum beating, is built up with two oscillating spin conductance components which have different periods of oscillation related to the splitting of Dirac's energies in the FB region. The amplitudes of oscillations of Gq, Gs and TMR are not seen to decrease as the thickness increases. The decaying behaviors seen in the conventional transport through an insulator do not appear. 相似文献
99.
Guanghui Xu Qiang Zhang Weiping Zhou Jiaqi Huang Fei Wei 《Applied Physics A: Materials Science & Processing》2008,92(3):531-539
This study sought to produce carbon nanotube (CNT) pulp out of extremely long, vertically aligned CNT arrays as raw materials.
After high-speed shearing and mixing nitric acid and sulfuric acid, which served as the treatment, the researchers produced
the desired pulp, which was further transformed into CNT paper by a common filtration process. The paper’s tensile strength,
Young’s modulus and electrical conductivity were 7.5 MPa, 785 MPa and 1.0×104 S/m, respectively, when the temperature of the acid treatment was at 110°C. Apart from this, the researchers also improved
the mechanical property of CNT paper by polymers. The CNT paper was soaked in polyethylene oxide, polyvinyl pyrrolidone, and
polyvinyl alcohol (PVA) solution, eventually making the CNT/PVA film show its mechanical properties, which increased, while
its electrical conductivity decreased. To diffuse the polymer into the CNT paper thoroughly, the researchers used vacuum filtration
to fabricate a CNT/PVA film by penetrating PVA into the CNT paper. After a ten-hour filtration, the tensile strength and Young’s
modulus of CNT/PVA film were 96.1 MPa and 6.23 GPa, respectively, which show an increase by factors of 12 and 7, respectively,
although the material’s electrical conductivity was lowered to 0.16×104 S/m. 相似文献
100.
Y.-X. Wang S.-J. Xiong 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,67(1):63-69
We investigate localization behavior of electron states in bilayer graphene formed with the Bernal stacking in the presence
of various types of disorder (site-energy, in-plane hopping and inter-plane hopping) by the use of the transfer matrix method.
It is found that all the states are localized at various kinds of disorder (site-energy, in-plane hopping and inter-plane
hopping) except that in the case of inter-plane-hopping disorder the states at the zero energy are critical. The implications
of the results are discussed. 相似文献