共查询到20条相似文献,搜索用时 15 毫秒
1.
G.S. Duesberg J. Muster V. Krstic M. Burghard S. Roth 《Applied Physics A: Materials Science & Processing》1998,67(1):117-119
Received: 18 May 1998/Accepted: 22 May 1998 相似文献
2.
J. Lefebvre R. Antonov A.T. Johnson 《Applied Physics A: Materials Science & Processing》1998,67(1):71-74
Received: 10 February 1998 相似文献
3.
Y-branching of single walled carbon nanotubes 总被引:1,自引:0,他引:1
P. Nagy R. Ehlich L.P. Biró J. Gyulai 《Applied Physics A: Materials Science & Processing》2000,70(4):481-483
Y-branching was observed by scanning tunnelling microscopy (STM) in single wall carbon nanotubes grown by thermal decomposition
of C60 fullerene in the presence of transition metals. These novel carbon nanostructures may play an important role in carbon-based
nanoelectronics.
Received: 18 November 1999 / Accepted: 20 January 2000 / Published online: 8 March 2000 相似文献
4.
A theoretical model for the growth of single-wall carbon nanotubes produced by metal-catalyzed decomposition of hydrocarbons
and fullerenes is presented. The growth process is treated as a thermodynamic equilibrium between carbon in the gas phase
and carbon in the nanotube. The minimum possible nanotube diameters based on several published experimental conditions are
calculated by combining the free energy of the reaction with an equation derived from elastic theory. The model predicts the
possibility of generating nanotubes with extremely small diameters that are smaller than in the corresponding experiments.
Received: 18 July 2001 / Accepted: 19 November 2001 / Published online: 4 March 2002 相似文献
5.
G.S. Duesberg J. Muster H.J. Byrne S. Roth M. Burghard 《Applied Physics A: Materials Science & Processing》1999,69(3):269-274
Production methods for carbon nanotubes are now well established and allow their synthesis on a scale of grams per day. For
many potential applications of this unique material, its purification still remains a crucial problem. In this article various
purification methods for single- and multi-wall carbon nanotubes are reviewed. These methods are compared in terms of their
capacity, efficiency, and effects on the tubes. In addition, the use of Raman spectroscopy for monitoring the chromatographic
purification of single-wall nanotubes is described.
Received: 17 May 1999 / Accepted: 18 May 1999 / Published online: 29 July 1999 相似文献
6.
A. Boschetti D. Bassi E. Iacob S. Iannotta L. Ricci M. Scotoni 《Applied physics. B, Lasers and optics》2002,74(3):273-278
A compact multi-component trace-gas detector based on the resonant photoacoustic technique and a NIR external cavity diode
laser has been developed. It has been characterized using a mixture of ethylene and methane diluted in ambient air. A spectroscopic
investigation of combination bands and overtones between 5900 and 6250 cm-1, obtained with an IR pulsed laser photoacoustic spectrometer, allowed us to find a wavelength region where the 2ν3 overtone of CH4 and the ν5+ν9 combination band of C2H4 show uncongested rotational lines. Using a single-mode scan of the diode laser in this region, around 6150 cm-1, the sensitivity for the simultaneous detection of ethylene and methane is 8 ppm/mW and 40 ppm/mW respectively. Factors affecting
the sensitivity and selectivity of the detection system and possible improvements suitable to reach the sub-ppm detection
limit are discussed.
Received: 1 August 2001 / Revised version: 28 November 2001 / Published online: 7 February 2002
An erratum to this article is available at . 相似文献
7.
F. Kokai K. Takahashi D. Kasuya M. Yudasaka S. Iijima 《Applied Physics A: Materials Science & Processing》2001,73(4):401-407
Single-wall carbon nanotubes (SWNTs) were synthesized by the irradiation of 20-ms CO2 laser pulses onto a graphite–Co/Ni target at room temperature. We investigated the effect of laser power density (10–150 kW/cm2) and ambient Ar gas pressure (150–760 Torr) on the abundance of SWNTs with lengths of up to about 200 nm in soot-like carbonaceous
deposits. For a constant power density (30 kW/cm2), depending on the Ar gas pressure, SWNTs with diameters of 1.2–1.4 nm were synthesized. Expansion behavior and temperature-fall
rates of clusters and/or particles in laser plumes were also analyzed by high-speed video imaging and temporally and spatially
resolved emission spectroscopy. The temperature-fall rates were estimated to be 171–427 K/ms. The SWNT growth on the time
scale of a few milliseconds appeared to be related to some features of condensing clusters and/or particles, including resident
densities, collision frequencies and temperatures.
Received: 16 July 2001 / Accepted: 23 July 2001 / Published online: 30 August 2001 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.
Synthesis and Raman characterization of mono-sized single-wall carbon nanotubes in one-dimensional channels of AlPO4-5 crystals 总被引:1,自引:0,他引:1
H.D. Sun Z.K. Tang J. Chen G. Li 《Applied Physics A: Materials Science & Processing》1999,69(4):381-384
Mono-sized single-wall carbon nanotubes were formed in one-dimensional channels of AlPO4-5 single crystal (AFI) by pyrolysis of tripropylamine (TPA). Raman spectra have been measured for the TPA-AFI crystals thermally
processed at different conditions. TPA molecules are carbonized at 400 °C, and carbon nanotubes were formed at 500 °C or above.
The radial-breathing mode, which is special for carbon nanotube geometry, was observed. Three Raman-active modes with symmetry
A
1g, E
1g, and E
2g were identified by detailed symmetrical analysis for the polarized-Raman spectra.
Received: 29 October 1998 / Accepted: 29 March 1999 / Published online: 24 June 1999 相似文献
10.
S. Bandow F. Kokai K. Takahashi M. Yudasaka S. Iijima 《Applied Physics A: Materials Science & Processing》2001,73(3):281-285
The magnetic properties of single-wall carbon nanohorns (SWNH) were studied by electron spin resonance (ESR) and static magnetic
susceptibility measurements. The SWNHs were ESR active with linewidth (ΔH) of ∼6 G in vacuo at room temperature. ΔH was susceptible
to the partial pressure of O2 and became 53 G at 1 atmospheric pressure of O2, while the integrated ESR intensity was independent on O2 pressure and behaved as Curie-like, suggesting an intrinsic ESR origin with localized electron spin character. The diamagnetic
susceptibility for SWNHs indicated a value smaller than that of randomly oriented graphite by an order of magnitude, but showing
a magnitude comparable to those of C60 and C70. It is suggested that the large diamagnetism expecting for sp2 networked carbon materials will be canceled by the Van Vleck constant paramagnetism.
Received: 20 November 2000 / Accepted: 21 November 2000 / Published online: 25 July 2001 相似文献
11.
Gas monitoring in the process industry using diode laser spectroscopy 总被引:10,自引:0,他引:10
2 , CO, NH3, HCl and HF are described together with measurements from several installations. The monitors show continuous measurements
with fast response and good sensitivity, all of which is difficult to obtain with conventional techniques such as wet chemical
analysis.
Received: 19 March 1998/Revised version: 2 June 1998 相似文献
12.
The technique of photothermal deflection spectroscopy (PTDS) is investigated for temperature measurements in a flame. The
spatial distribution of temperature is measured in two different types of burners operating with methane and oxygen, and methane
and air. The spatial distributions of the temperature are in qualitative agreement with our expectations. At two points, the
temperatures measured by PTDS have been compared with those measured by Boltzmann distributions. The measurements agree within
their uncertainties. All the effects that affect the reliability of this technique are investigated and discussed. Finally,
the pros and cons of the PTDS technique for temperature measurement are discussed.
Received: 31 January 2002 / Published online: 8 August 2002 相似文献
13.
Spectroscopic properties and STM images of carbon nanotubes 总被引:2,自引:0,他引:2
A. Rubio 《Applied Physics A: Materials Science & Processing》1999,68(3):275-282
Received: 23 November 1998 / Accepted: 22 December 1998 相似文献
14.
K. Shimotani K. Anazawa H. Watanabe M. Shimizu 《Applied Physics A: Materials Science & Processing》2001,73(4):451-454
We have synthesized multi-walled carbon nanotubes (MWNTs) using a DC arc discharge method under organic molecular atmospheres.
This method allows us to synthesize about five times more MWNTs than are synthesized using the usual arc discharge method,
using discharge conditions of 100 A and 20 V. We have examined the synthetic yield of MWNTs at various pressures under different
organic atmospheres. The yield of MWNTs increases with the number of carbon atoms in the organic molecule.
Received: 21 September 2000 / Accepted: 18 December 2000 / Published online: 26 April 2001 相似文献
15.
E. Arimondo F. Calderazzo F. Fuso C. Toffi 《Applied Physics A: Materials Science & Processing》1998,66(4):407-411
2 . The dependence of the ion production on the laser ablation parameters is investigated and the expansion dynamics of the
ablated species is studied through time and space resolved measurements of the ion yield. We discuss our observations on the
basis of reactions involving neutral and ionized carbon-based species.
Received: 11 March 1997/Accepted: 30 June 1997 相似文献
16.
D.D. Nelson J.H. Shorter J.B. McManus M.S. Zahniser 《Applied physics. B, Lasers and optics》2002,75(2-3):343-350
Non-cryogenic, laser-absorption spectroscopy in the mid-infrared has wide applications for practical detection of trace gases
in the atmosphere. We report measurements of nitric oxide in air with a detection limit less than 1 nmole/mole (<1 ppbv) using
a thermoelectrically cooled quantum cascade laser operated in pulsed mode at 5.26 μm and coupled to a 210-m path length multiple-pass
absorption cell at reduced pressure (50 Torr). The sensitivity of the system is enhanced by operating under pulsing conditions
which reduce the laser line width to 0.010 cm-1 (300 MHz) HWHM, and by normalizing pulse-to-pulse intensity variations with temporal gating on a single HgCdTe detector.
The system is demonstrated by detecting nitric oxide in outside air and comparing results to a conventional tunable diode
laser spectrometer sampling from a common inlet. A detection precision of 0.12 ppb Hz-1/2 is achieved with a liquid-nitrogen-cooled detector. This detection precision corresponds to an absorbance precision of 1×10-5 Hz-1/2 or an absorbance precision per unit path length of 5×10-10 cm-1 Hz-1/2. A precision of 0.3 ppb Hz-1/2 is obtained using a thermoelectrically cooled detector, which allows continuous unattended operation over extended time periods
with a totally cryogen-free instrument.
Received: 1 May 2002 / Revised version: 6 June 2002 / Published online: 21 August 2002
RID="*"
ID="*"Corresponding author. Fax: +1-978/663-4918, E-mail: ddn@aerodyne.com 相似文献
17.
Tuning and stability of a continuous-wave mid-infrared high-power single resonant optical parametric oscillator 总被引:1,自引:0,他引:1
M.M.J.W. van Herpen S. Li S.E. Bisson S. te Lintel Hekkert F.J.M. Harren 《Applied physics. B, Lasers and optics》2002,75(2-3):329-333
A 2.2-W continuous-wave, continuously tunable, single-frequency OPO has been developed in the 3.0–3.8 μm wavelength range
for the detection of molecular trace gasses. The oscillation threshold, output power and stability of the single resonant
OPO were improved by optimizing pump beam waist and OPO cavity length. Both air-spaced and solid etalons were tested to frequency
stabilize and tune the OPO, from which the solid etalon gave a better performance. Temperature oscillations in the PPLN crystal
caused oscillations in the idler wavelength of less than 200 MHz over 300 s; the short-term stability was less than 3 MHz
over 1 s. The high laser power, in combination with photoacoustic spectroscopy, achieved a detection limit of 10 parts-per-trillion
for ethane in nitrogen.
Received: 9 April 2002 / Revised version: 14 June 2002 / Published online: 2 September 2002
RID="*"
ID="*"Corresponding author. Fax:+31-24/3653311, E-Mail: maartenh@sci.kun.nl 相似文献
18.
L. Menzel A.A. Kosterev R.F. Curl F.K. Tittel C. Gmachl F. Capasso D.L. Sivco J.N. Baillargeon A.L. Hutchinson A.Y. Cho W. Urban 《Applied physics. B, Lasers and optics》2001,72(7):859-863
Two configurations of a continuous wave quantum cascade distributed feedback laser-based gas sensor for the detection of NO
at a parts per billion (ppb) concentration level, typical of biomedical applications, have been investigated. The laser was
operated at liquid nitrogen temperature near λ=5.2 μm. In the first configuration, a 100 m optical path length multi-pass
cell was employed to enhance the NO absorption. In the second configuration, a technique based on cavity-enhanced spectroscopy
(CES) was utilized, with an effective path length of 670 m. Both sensors enabled simultaneous analysis of NO and CO2 concentrations in exhaled air. The minimum detectable NO concentration was found to be 3 ppb with a multi-pass cell and 16 ppb
when using CES. The two techniques are compared, and potential future developments are discussed.
Received: 1 November 2000 / Revised version: 19 January 2001 / Published online: 20 April 2001 相似文献
19.
We demonstrate the use of photothermal deflection spectroscopy for a simultaneous measurement of absolute minority-species
concentration, temperature and flow velocity in a flame from the analysis of a single data trace. The ability to make absolute
concentration measurements, as well as the ability to measure three important combustion parameters simultaneously, may make
this technique quite useful in many circumstances.
Received: 27 August 2002 / Revised version: 26 September 2002 / Published online: 11 December 2002
RID="*"
ID="*"Corresponding author. Fax: +1-479/575-4580, E-mail: rgupta@uark.edu 相似文献
20.
Single-walled carbon nanotubes (SWNTs) encapsulating C70s, so-called C70 peapods, were synthesized in high yield by a vapor-phase doping method. Raman spectra, high resolution transmission electron microscopy (HRTEM), and selected area electron diffraction (SAED) measurement indicate that the tube diameter is one of the important factors to determine the orientation of C70 molecules inside the SWNTs. SWNTs with different diameters give different alignment of C70 molecules. The lying orientation is favorable over the standing orientation in thin nanotube, i.e. 1.36 nm nanotubes, whereas the standing orientation is favorable in thick nanotubes, i.e. 1.49 and 1.61 nm nanotubes. 相似文献