Growth of single-wall carbon nanotubes dependent on laser power density and ambient gas pressure during room-temperature CO2 laser vaporization

ABSTRACTHard amorphous carbon films have been deposited by ArF pulsed laser ablation of graphite at room temperature, with the laser power density of 5x108 W/cm2. The films prepared in the high vacuum environment possess remarkable diamond-like properties with a hardness up to 38 GPa and an optical energy band gap of 2.4 eV. The properties of the films doped with nitrogen vary with the nitrogen content, but improve interface adhesion, resulting in the extension of the film thickness limit to a greater range. The results suggest that the properties of the laser ablation deposited diamond-like carbon films depend not only on the laser power density, but also strongly on the laser wavelength or photon energy.

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Influence of Saturation Phenomena on Laser-Excited Atomic Fluorescence Flame Spectrometry

Zeitschrift für Naturforschung A ◽

10.1515/zna-1973-0220 ◽

1973 ◽

Vol 28 (2) ◽

pp. 273-279

Author(s):

J. Kühl ◽

S. Neumann ◽

M. Kriese

Keyword(s):

Power Density ◽

Laser Power ◽

Atomic Emission ◽

Equation Model ◽

Laser Power Density ◽

Atomic Level ◽

Dye Laser ◽

Atomic Fluorescence ◽

Emission Flame ◽

Flame Spectrometry

Using a simple rate equation model, the laser power density Ic necessary to reach 50% of the saturation limited population of the excited atomic level under typical flame conditions is calculated. For Na atoms aspirated into the flame a saturating power density for irradiation with a narrow dye laser line (bandwidth 0.033 Å) of Ic ~ 0.4 kW/cm2 was determined. With the aid of a dye laser with an appropriate laser power density, analytical curves for Na were measured yielding a detection limit of 0.2 ng/ml. This sensitivity is comparable with the best results obtained by atomic emission flame spectrometry.

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Experimental Study on Testing Ni-Containing Stainless Steel Protective Coatings by Pulsed Laser Scratching

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.43.651 ◽

2010 ◽

Vol 43 ◽

pp. 651-656

Author(s):

Ai Xin Feng ◽

Yu Peng Cao ◽

Chuan Chao Xu ◽

Huai Yang Sun ◽

Gui Fen Ni ◽

...

Keyword(s):

Residual Stress ◽

Stainless Steel ◽

Power Density ◽

Laser Power ◽

Protective Coatings ◽

Three Dimensional ◽

Pulsed Laser ◽

Laser Power Density ◽

The Matrix ◽

The Impact

In the experiment, we use pulsed laser to conduct discrete scratching on Ni-containing stainless steel protective coatings to test residual stress situation after the matrix is scratched; then to analyze the the impact of the impact stress wave on coating - substrate bonding strength according to the test results, finally to infer the laser power density range within which it occurs coating failure. The study shows that: after laser discrete scratching, the residual stress of the center of the laser-loaded point on matrix surface gradually reduces when the pulsed laser power density increases. The matrix produces a corresponding residual compressive stress under the laser power density reaches a certain value. The actual failure threshold values are 12.006 GW/cm2, 11.829GW/cm2 and 12.193GW/cm2 measured by the three-dimensional topography instrument testing the discrete scratch point of three groups of samples and verified by using a microscope

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Pressure Isotherms of Hydrogen Adsorption in Carbon Nanostructures

MRS Proceedings ◽

10.1557/proc-706-z9.11.1 ◽

2001 ◽

Vol 706 ◽

Cited By ~ 2

Author(s):

Xiaohong Chen ◽

Urszula Dettlaff-Weglikowska ◽

Miroslav Haluska ◽

Martin Hulman ◽

Siegmar Roth ◽

...

Keyword(s):

Carbon Nanotubes ◽

Activated Carbon ◽

Hydrogen Storage ◽

Carbon Nanostructures ◽

Room Temperature ◽

Storage Capacity ◽

Hydrogen Adsorption ◽

Single Wall Carbon Nanotubes ◽

Hydrogen Storage Capacity ◽

Carbon And Graphite

AbstractThe hydrogen adsorption capacity of various carbon nanostructures including single-wall carbon nanotubes, graphitic nanofibers, activated carbon, and graphite has been measured as a function of pressure and temperature. Our results show that at room temperature and a pressure of 80 bar the hydrogen storage capacity is less than 1 wt.% for all samples. Upon cooling, the capacity of hydrogen adsorption increases with decreasing temperature and the highest value was observed to be 2.9 wt. % at 50 bar and 77 K. The correlation between hydrogen storage capacity and specific surface area is discussed.

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Numerical Simulation and Applications of a Method for Attenuating Laser Power Density

Laser & Optoelectronics Progress ◽

10.3788/lop50.022201 ◽

2013 ◽

Vol 50 (2) ◽

pp. 022201

Author(s):

王振宝 Wang Zhenbao ◽

冯国斌 Feng Guobin ◽

杨鹏翎 Yang Pengling ◽

冯刚 Feng Gang ◽

闫燕 Yan Yan

Keyword(s):

Numerical Simulation ◽

Power Density ◽

Laser Power ◽

Laser Power Density

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Formation of C60 using CO2 laser vaporization of graphite at room temperature

Chemical Physics Letters ◽

10.1016/s0009-2614(01)00139-7 ◽

2001 ◽

Vol 337 (1-3) ◽

pp. 25-30 ◽

Cited By ~ 18

Author(s):

Daisuke Kasuya ◽

Fumio Kokai ◽

Kunimitsu Takahashi ◽

Masako Yudasaka ◽

Sumio Iijima

Keyword(s):

Co2 Laser ◽

Room Temperature ◽

Laser Vaporization

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Encapsulated Fullerenes Within Single Wall Carbon Nanotubes

Microscopy and Microanalysis ◽

10.1017/s1431927600014239 ◽

1999 ◽

Vol 5 (S2) ◽

pp. 182-183

Author(s):

Brian W. Smith ◽

David E. Luzzi

Keyword(s):

Electron Microscopy ◽

Carbon Nanotubes ◽

Pulsed Laser ◽

Irradiation Damage ◽

Laser Vaporization ◽

Single Wall Carbon Nanotubes ◽

Phase Object ◽

Parallel Lines ◽

Weak Phase ◽

Transmission Electron

It is well documented that the pulsed laser vaporization of graphite produces both carbon nanotubes and C60 in the presence of certain metallic catalysts. In nanotube production most of the Ceo is removed along with other residual contaminants during succeeding purification and annealing steps. The possibility of C60 becoming trapped inside a nanotube during this elaborate sequence has been considered but not previously detected.Nanotubes are observed with high resolution transmission electron microscopy under conditions chosen to minimize both exposure time and irradiation damage. Since a nanotube satisfies the weak phase object approximation, its image is a projection of the specimen -potential in the direction of the electron beam. The image has maximum contrast where the beam encounters the most carbon atoms, which occurs where it is tangent to the tube’s walls. Thus, the image consists of two dark parallel lines whose separation is equal to the tube diameter, 1.4 nm.

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