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1.
Field emission from carbon nanotubes: perspectives for applications and clues to the emission mechanism 总被引:15,自引:0,他引:15
J.-M. Bonard J.-P. Salvetat T. Stöckli L. Forró A. Châtelain 《Applied Physics A: Materials Science & Processing》1999,69(3):245-254
We report on the extensive characterization of carbon nanotube electron field emitters. We studied the emission behavior of
single-wall, closed and opened arc-discharge multi-wall, and catalytically grown multi-wall nanotubes, as single emitters
and in film form. The nanotube field emitters show excellent field emission properties, but significant differences were observed
between the different types of nanotubes. To obtain good performances as well as long emitter lifetimes, the nanotubes should
be multi-walled and have closed, well-ordered tips. Complementary results such as energy distribution and luminescence induced
by the field emission give further precious indications on the field emission mechanism. The large field amplification factor,
arising from the small radius of curvature of the nanotube tips, is partly responsible for the good emission characteristics.
Additional evidence however shows that the density of states at the tip is non-metallic, appearing in the form of localized
states with well-defined energy levels.
Received: 15 May 1999 / Accepted: 18 May 1999 / Published online: 29 July 1999 相似文献
2.
M. Waiblinger Ch. Sommerhalter B. Pietzak J. Krauser B. Mertesacker M.Ch. Lux-Steiner S. Klaumünzer A. Weidinger C. Ronning H. Hofsäß 《Applied Physics A: Materials Science & Processing》1999,69(2):239-240
Electrically conducting channels in an insulating carbon matrix were produced by 140-MeV Xe ion irradiation. The high local
energy deposition of the individual ions along their pathes causes a rearrangement of the carbon atoms and leads to a transformation
of the insulating, diamond-like (sp3-bonding) form of carbon into the conducting, graphitic (sp2-bonding) configuration. The conducting ion tracks are clearly seen in the current mapping performed with an atomic force
microscope (AFM). These conducting tracks are of possible use in field emission applications.
Received: 4 May 1999 / Accepted: 5 May 1999 / Published online: 1 July 1999 相似文献
3.
Application of scanning force microscopy in nanotube science 总被引:2,自引:0,他引:2
J. Muster G.S. Duesberg S. Roth M. Burghard 《Applied Physics A: Materials Science & Processing》1999,69(3):261-267
Recent developments in the application of scanning force microscopy in nanotube science are reviewed. The non-destructive
character of this technique allows the structural characterisation of (chemically modified) single- and multi-wall nanotubes
deposited on substrates for further investigations such as electrical transport measurements. Furthermore, SFM is now an established
tool for manipulation of nanotubes, which allows position control and determination of elastic constants such as the Young’s
modulus. Finally it is shown that very sharp and stable probes for scanning force microscopy can be made from nanotubes due
to their excellent stability and aspect ratio.
Received: 17 May 1999 / Accepted: 18 May 1999 / Published online: 29 July 1999 相似文献
4.
A. Milekhin M. Friedrich D.R.T. Zahn L. Sveshnikova S. Repinsky 《Applied Physics A: Materials Science & Processing》1999,69(1):97-100
Structures with CdS quantum dots produced by the Langmuir–Blodgett (LB) technique were investigated by Raman, IR, and UV spectroscopies.
The confinement effect of longitudinal optical (LO) phonons in CdS quantum dots was investigated by Raman spectroscopy. Surface
vibrational modes of CdS quantum dots were observed in IR spectra. It was shown experimentally that the frequency of the surface
vibrational modes depends on the properties of the surrounding media. An average size of CdS quantum dots of about 3–6.4 nm
was obtained from the analysis of UV measurements.
Received: 1 February 1999 / Accepted: 1 April 1999 / Published online: 19 May 1999 相似文献
5.
J. Nygard D.H. Cobden M. Bockrath P.L. McEuen P.E. Lindelof 《Applied Physics A: Materials Science & Processing》1999,69(3):297-304
We review transport measurements on single-walled carbon nanotubes contacted by metal electrodes. At room temperature some
devices show transistor action similar to that of p-channel field effect transistors, while others behave as gate-voltage
independent wires. At low temperatures transport is usually dominated by Coulomb blockade. In this regime the quantum eigenstates
of the finite-length tubes can be studied. At higher temperatures power law behaviour is observed for the temperature and
bias dependence of the conductance. This is consistent with tunneling into a one-dimensional Luttinger liquid in a nanotube.
We also discuss recent developments in contacting nanotubes which should soon allow study of their intrinsic transport properties.
Received: 17 May 1999 / Accepted 18 May 1999 / Published online: 4 August 1999 相似文献
6.
F. Decremps M. Fischer A. Polian M. Sieskind 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,5(1):7-13
The sound velocities for longitudinal and transverse waves have been measured in single crystalline BaFCl at room temperature
using ultrasonic pulse echo and Brillouin scattering techniques. The complete set of elastic constants is deduced and lead
to the bulk moduli values of BaFCl at ambiant conditions (, , ) which are compared with those obtained by a shell model. Moreover, using the ultrasonic technique under pressure, the pressure
derivatives of the second order elastic constants at 298 K have been determined up to 0.3 GPa. All moduli increase linearly
with pressure in this pressure range, allowing to determine directly and separately the first derivative of the bulk modulus
B'0 = 5.8. These data are used to calculate a Murnaghan equation of state. A detailed comparison is given between our results
with those recently obtained by X-ray diffraction on powder or calculated using the local density approximation method. Finally,
the anisotropy of BaFCl under pressure is discussed.
Received: 19 March 1998 / Revised: 15 May 1998 /
Accepted: 19 May 1998 相似文献
7.
M. Das M. Purkait C. R. Mandal 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,8(1):13-18
The Classical Trajectory Monte-Carlo (CTMC) simulation method has been employed to calculate the total electron capture cross-sections
with sub-shell distributions and ionization cross-sections in collision of B
q+
(q=1-4) with ground state atomic hydrogen in the energy range of 10-200 keV/amu. The computed results have been observed to be in
reasonable agreement with other existing theoretical and experimental results over the entire energy region considered.
Received 23 February 1999 and Received in final form 23 May 1999 相似文献
8.
Scanning tunneling microscopy of carbon nanotubes 总被引:1,自引:0,他引:1
W. Clauss 《Applied Physics A: Materials Science & Processing》1999,69(3):275-281
This article reports on the application of scanning tunneling microscopy for the study of surface structures and electronic
properties of carbon nanotubes. Geometric effects resulting from the cylindrical shape of the tubes as well as the particular
band structure of the graphitic crystal lattice can lead to a variety of contrast patterns. On the atomic scale, it is sometimes
possible to see the full honeycomb lattice structure but often different structures are observed. Besides distortions caused
by tip–sample interactions, we find that a complex superstructure superimposed on the simple atomic contrast pattern arises
from elastic scattering of the Fermi states at defects or impurities. From a careful analysis of high-resolution images it
is possible to extract information about elastic strain of individual tubes. A new combination of scanning tunneling and scanning
force microscopy enables near-atomic point resolution of the force signal the tubes can be identified without the need of
a conducting substrate. This imaging mode is a crucial step for the characterization of electronic devices based on individual
single-wall tubes. This mode can be further enhanced by the use of single-walled tubes as probe tips.
Received: 17 May 1999 / Accepted: 18 May 1999 / Published online: 4 August 1999 相似文献
9.
Template-based synthesis of nanomaterials 总被引:13,自引:0,他引:13
A. Huczko 《Applied Physics A: Materials Science & Processing》2000,70(4):365-376
The large interest in nanostructures results from their numerous potential applications in various areas such as materials
and biomedical sciences, electronics, optics, magnetism, energy storage, and electrochemistry. Ultrasmall building blocks
have been found to exhibit a broad range of enhanced mechanical, optical, magnetic, and electronic properties compared to
coarser-grained matter of the same chemical composition. In this paper various template techniques suitable for nanotechnology
applications with emphasis on characterization of created arrays of tailored nanomaterials have been reviewed. These methods
involve the fabrication of the desired material within the pores or channels of a nanoporous template. Track-etch membranes,
porous alumina, and other nanoporous structures have been characterized as templates. They have been used to prepare nanometer-sized
fibrils, rods, and tubules of conductive polymers, metals, semiconductors, carbons, and other solid matter. Electrochemical
and electroless depositions, chemical polymerization, sol-gel deposition, and chemical vapour deposition have been presented
as major template synthetic strategies. In particular, the template-based synthesis of carbon nanotubes has been demonstrated
as this is the most promising class of new carbon-based materials for electronic and optic nanodevices as well as reinforcement
nanocomposites.
Received: 27 May 1999 / Accepted: 27 October 1999 / Published online: 8 March 2000 相似文献
10.
M. Ramm M. Ata T. Gross W. Unger 《Applied Physics A: Materials Science & Processing》2000,70(4):387-390
We report core-level and valence-band X-ray photoelectron spectroscopy (XPS) and carbon [
]K near-edge X-ray-absorptionfine structure spectroscopy (NEXAFS) results of plasma-polymerized C60. In comparison with evaporated C60 the C 1s peak is broader and asymmetric for the C60 polymer and its shake-up satellites diminished. Furthermore, the features of the valence-band as well as the features of
the π* antibonding orbitals of the C60 polymer are broader and reduced in intensity. Changes in the electronic structure are attributed to the polymerization of
C60, the post-plasma functionalization of the surface by oxygen after exposure to atmosphere, and the occurrence of amorphous
carbon.
Received: 28 May 1999 / Accepted: 31 August 1999 / Published online: 8 March 2000 相似文献
11.
Mechanical properties of carbon nanotubes 总被引:26,自引:0,他引:26
J.-P. Salvetat J.-M. Bonard N.H. Thomson A.J. Kulik L. Forró W. Benoit L. Zuppiroli 《Applied Physics A: Materials Science & Processing》1999,69(3):255-260
A variety of outstanding experimental results on the elucidation of the elastic properties of carbon nanotubes are fast appearing.
These are based mainly on the techniques of high-resolution transmission electron microscopy (HRTEM) and atomic force microscopy
(AFM) to determine the Young’s moduli of single-wall nanotube bundles and multi-walled nanotubes, prepared by a number of
methods. These results are confirming the theoretical predictions that carbon nanotubes have high strength plus extraordinary
flexibility and resilience. As well as summarising the most notable achievements of theory and experiment in the last few
years, this paper explains the properties of nanotubes in the wider context of materials science and highlights the contribution
of our research group in this rapidly expanding field. A deeper understanding of the relationship between the structural order
of the nanotubes and their mechanical properties will be necessary for the development of carbon-nanotube-based composites.
Our research to date illustrates a qualitative relationship between the Young’s modulus of a nanotube and the amount of disorder
in the atomic structure of the walls. Other exciting results indicate that composites will benefit from the exceptional mechanical
properties of carbon nanotubes, but that the major outstanding problem of load transfer efficiency must be overcome before
suitable engineering materials can be produced.
Received: 17 May 1999 / Accepted: 18 May 1999 / Published online: 29 July 1999 相似文献
12.
S.I. Anisimov N.A. Inogamov A.M. Oparin B. Rethfeld T. Yabe M. Ogawa V.E. Fortov 《Applied Physics A: Materials Science & Processing》1999,69(6):617-620
Theoretical study of laser ablation is usually based on the assumption that the vapor is an ideal gas. Its flow is described
by gas dynamics equations [1, 2]. The boundary conditions at vaporization front are derived from the solution of the Boltzmann
equation that describes the vapor flow in the immediate vicinity of the vaporizing surface (so-called Knudsen layer) [1].
This model is applicable within the range of temperatures much lower than the critical temperature of target material. In
the present work, a general case is considered when the temperature of the condensed phase is comparable to or higher than
the critical temperature. The dynamics of both condensed and gaseous phases can be described in this case by the equations
of hydrodynamics. The dynamics of vaporization of a metal heated by an ultrashort laser pulse is studied both analytically
and numerically. The analysis reveals that the flow consists of two domains: thin liquid shell moving with constant velocity,
and thick low-density layer of material in two-phase state.
Received: 2 March 1999 / Accepted: 28 May 1999 / Published online: 21 October 1999 相似文献
13.
Effect of gas pressure on the growth and structure of carbon nanotubes by chemical vapor deposition 总被引:3,自引:0,他引:3
W.Z. Li J.G. Wen Y. Tu Z.F. Ren 《Applied Physics A: Materials Science & Processing》2001,73(2):259-264
The effect of gas pressure on the structure of carbon nanotubes (CNTs) has been systematically investigated in the chemical
vapor deposition process. The yield of CNTs (defined as the weight ratio of CNTs vs. catalyst) increases significantly with
the gas pressure, reaches 600% at 600 Torr, then decreases with further increase of gas pressure. At low reacting gas pressure
the CNTs have completely hollow cores, whereas at high pressure the CNTs have a bamboo structure. The density of the compartments
in the bamboo-structured CNTs increases dramatically with the increase of the gas pressure. This result shows that the structure
and yield of carbon nanotubes are strongly affected by the growth gas pressure.
Received: 10 May 2001 / Accepted: 10 May 2001 / Published online: 20 June 2001 相似文献
14.
M.B. Smith G.J. Campbell R. Chapman P.O. Tjøm R.A. Bark G.B. Hagemann N. Keeley D.J. Middleton H. Ryde K.-M. Spohr 《The European Physical Journal A - Hadrons and Nuclei》1999,5(1):37-42
High-spin states in 167Hf, populated in the 141Pr(30Si, p3n)167Hf reaction, have been studied using the nordball Ge detector array. Three rotational cascades have been observed for the first time and the previously-known level scheme
has been extended to significantly higher spin. Band-crossing effects are discussed within the framework of Woods-Saxon cranking
calculations and are found to be in good agreement.
Received: 9 April 1999 / Revised version: 13 May 1999 相似文献
15.
K. Sokolowski-Tinten A. Cavalleri D. von der Linde 《Applied Physics A: Materials Science & Processing》1999,69(5):577-579
We describe a new technique for optical pump–probe measurements at femtosecond excited surfaces. By combining time-resolved
microscopy with cylindrical focusing of the pump, complete mapping of the time and fluence dependence of laser-induced optical
changes becomes possible in a single-pulse experiment.
Received: 16 August 1999 / Accepted: 17 August 1999 / Published online: 30 September 1999 相似文献
16.
We report a new imaging diagnostic suitable for measurements of infrared-active molecules, namely infrared planar laser-induced
fluorescence (IR PLIF), in which a tunable infrared source is used to excite vibrational transitions in molecules and vibrational
fluorescence is collected by an infrared camera. A nanosecond-pulse Nd:YAG-pumped KTP/KTA OPO/OPA system is used to generate
12 mJ of tunable output near 2.35 μm which excites the 2ν band of carbon monoxide (CO); fluorescence resulting from excited
CO is collected at 4.7 μm by using an InSb focal plane array. Quantitative, high-SNR PLIF imaging of gas-phase CO is demonstrated
at a 10-Hz acquisition rate with a minimum detection limit of 1350 ppm at 300 K.
Received: 30 July 1999 / Published online: 16 September 1999 相似文献
17.
A.N. Obraztsov I.Yu. Pavlovsky V.G. Ralchenko H. Okushi H. Watanabe 《Applied Physics A: Materials Science & Processing》1999,68(6):663-666
A novel method of determination of polycrystalline diamond films’ thermoconductive properties using the photoacoustic effect
is proposed. By this method, we studied the diamond films grown on silicon substrates using chemical vapor deposition technique.
A value of thermal conductivity obtained for the films was less than half that for diamond single crystal. The decrease of
thermal conductivity, as well as characteristic features of optical properties of the films, is explained by the presence
of a large amount of intercrystallite boundaries and other structure defects and admixures detected using Raman and photoluminescent
spectroscopies.
Received: 22 October 1998 / Accepted: 27 January 1999 / Published online: 28 April 1999 相似文献
18.
S. Rols E. Anglaret J.L. Sauvajol G. Coddens A.J. Dianoux 《Applied Physics A: Materials Science & Processing》1999,69(6):591-596
Elastic and inelastic neutron scattering are used to study the structure and dynamics of single-wall carbon nanotubes (SWNT)
self-assembled into nanobundles (NBSWNT). Suspensions of NBSWNT are characterized by small-angle neutron scattering. Neutron
diffraction is used as a useful tool to study the structure of both the SWNT and NBSWNT. Calculations on finite-size bundles
are compared to the data in order to estimate the distribution of tube diameters. Finally, we present time of flight inelastic
scattering measurements of the phonon density of states and discuss the main features of the spectra in comparison with calculations.
Received: 9 June 1999 / Accepted: 3 August 1999 / Published online: 27 October 1999 相似文献
19.
D.N. Kozlov B. Hemmerling A. Stampanoni-Panariello 《Applied physics. B, Lasers and optics》2000,71(4):585-591
We used time-resolved light scattering of cw probe laser radiation from laser-induced electrostrictive gratings for the determination
of flow velocities in air at room temperature. Some possibilities of the technique have been experimentally demonstrated with
submerged planar air jets in atmosphere, both for accumulated and single-shot measurements. The range of investigated flow
velocities was 5–200 m/s. The method of data treatment and of the estimate of the experimental parameters is described.
Received: 8 Febuary 2000 / Revised version: 2 May 2000 / Published online: 2 August 2000 相似文献
20.
G. Srinivasan T.P. Mullin D. Hanna A. Manivannan M.S. Seehra 《Applied Physics A: Materials Science & Processing》2001,72(3):333-339
The nature of the double-exchange (DE) interaction in lanthanum manganites is studied through chemical substitutions, Cs for
La, and high-pressure measurements. Static and high-frequency magnetic measurements and high-pressure electrical transport
studies were carried out on bulk polycrystalline and radio-frequency sputtered thin films of La0.7-xCsxCa0.3MnO3 for x=0-0.1. The samples are found to be cubic. Curie temperature Tc measurements provide evidence for bond-length-related weakening of DE as x is increased from 0 to 0.03. For higher x, the
bond-angle-related changes lead to an increase in the strength of DE. High-pressure mangetoresistance data indicate both bond
length and bond-angle-related increase of 10–20 K/GPa in Tc with pressure, with the largest increase measured for x=0.03. The rate of increase in the Curie temperature with pressure
decreases with increasing Tc. Anomalies are observed in the magnetic parameters for x=0.03. The Cs-concentration dependence of the low-temperature saturation
magnetization shows a minimum close to x=0.03. Ferromagnetic resonance studies at x-band reveal a 5% decrease in the g-value
for x=0.03 relative to the end members (x=0 and 0.1). The low-field magnetostriction for x=0.03 indicates a relatively strong
electron–phonon spin coupling compared to neighboring compositions.
Received: 15 May 2000 / Accepted: 24 July 2000 / Published online: 9 November 2000 相似文献