The main objective of this thesis is to find optimum discharge conditions in plasma reactors to realize controlled synthesis of various carbon-based materials with desired properties. Experimental conditions including substrate biasing, substrate pretreatment, gas flow rate, catalyst coating, and the type of carbon source, play important roles in controlling the nucleation and growth of carbon-based materials. In this Ph.D. work, the effects of various processing factors on nucleation and growth of carbon based materials were systematically investigated. The work has led to a better understanding of how each experimental parameter affects the carbon-based materials growth. Optimization of experiment conditions based on this understanding is beneficial for the controlled synthesis of carbon-based materials with desired properties. In addition, the controlled synthesis of tungsten-based nanostructures using a hot filament reactor was studied.<p>The main results presented in this thesis are: <p>(1) Synthesis of well-aligned carbon nanotube or carbon nanocone films with a glow discharge under a negative substrate biasing. The electric field in the plasma sheath above the substrate has been found to play an important role in controlling the alignment and orientation of nanotubes or nanocones. <p>(2) Synthesis of high purity diamond films using solid graphite as the carbon source by graphite etching. The technique provides a route to realizing deposition of high quality diamond films at low substrate temperatures (typically as low as 350 ℃). <p>(3) Successful synthesis of high quality diamond films on aluminum-coated steels using a graphite etching technique. The aluminum interlayer effectively reduces the graphitization which occurs on a steel substrate. <p>(4) Synthesis of nanocrystalline diamond films with smooth surfaces under high gas flow rates with a positive substrate biasing. Both high gas flow rate and positive biasing effectively increase the nucleation density of diamond and therefore reduce the diamond grain size. <p>(5) Synthesis of high purity crystalline tungsten or tungsten oxide nanorod films by optimizing the filament temperature in a hot filament reactor.

The main objective of this thesis is to find optimum discharge conditions in plasma reactors to realize controlled synthesis of various carbon-based materials with desired properties. Experimental conditions including substrate biasing, substrate pretreatment, gas flow rate, catalyst coating, and the type of carbon source, play important roles in controlling the nucleation and growth of carbon-based materials. In this Ph.D. work, the effects of various processing factors on nucleation and growth of carbon based materials were systematically investigated. The work has led to a better understanding of how each experimental parameter affects the carbon-based materials growth. Optimization of experiment conditions based on this understanding is beneficial for the controlled synthesis of carbon-based materials with desired properties. In addition, the controlled synthesis of tungsten-based nanostructures using a hot filament reactor was studied.<p>The main results presented in this thesis are: <p>(1) Synthesis of well-aligned carbon nanotube or carbon nanocone films with a glow discharge under a negative substrate biasing. The electric field in the plasma sheath above the substrate has been found to play an important role in controlling the alignment and orientation of nanotubes or nanocones. <p>(2) Synthesis of high purity diamond films using solid graphite as the carbon source by graphite etching. The technique provides a route to realizing deposition of high quality diamond films at low substrate temperatures (typically as low as 350 ℃). <p>(3) Successful synthesis of high quality diamond films on aluminum-coated steels using a graphite etching technique. The aluminum interlayer effectively reduces the graphitization which occurs on a steel substrate. <p>(4) Synthesis of nanocrystalline diamond films with smooth surfaces under high gas flow rates with a positive substrate biasing. Both high gas flow rate and positive biasing effectively increase the nucleation density of diamond and therefore reduce the diamond grain size. <p>(5) Synthesis of high purity crystalline tungsten or tungsten oxide nanorod films by optimizing the filament temperature in a hot filament reactor.

Nonpolar m-plane ZnO epitaxial film with [10-10] orientation and a-plane ZnO epitaxial film with [11-20]was successfully grown on a large-size [100] and [010] LiGaO2 (LGO) single crystal substrate by chemical vapor deposition (CVD) method. The dependence of growth characteristics on the different growth conditions was investigated. Following the CVD growth, the surface morphologies and epi-film crystallinity were studied by a scanning electron microscopy and X-ray diffraction. Room temperature photoluminescence spectra exhibit a strong near-band-edge emission peak at 377 nm with a negligible green band. Further structural characterizations and defect analysis of nonpolar ZnO material were performed using transmission electron microscope (TEM). This thesis included two different orientations ZnO film. First was ZnO[10-10], which can get good epi-film crystallinity and flat surface morphologies under 750¢J. And we tried to grow under different pressure, the data shown that higher pressure(more than 150 torr) tended to grow ZnO[10-10] orientation on LGO[100] substrate. The other one was ZnO[11-20]. We can get flat and continuous ZnO[11-20] film under 680¢J.

Thesis (M.S.) in Chemical Engineering--University of Maine, 2002. / Includes vita. Bibliography: leaves 58-62.

Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains xviii, 154 p.; also includes graphics (some col.). Includes abstract and vita. Advisor: Jeffery C. Rogers, Dept. of Atmospheric Science. Includes bibliographical references (p. 142-153).

Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.

The equilibrium partial pressures of monoethanolamine (MEA), piperazine (PZ), and water were measured in a stirred reactor with a recirculating vapor phase by FTIR analysis at 35 - 70 Celsius degrees. MEA and PZ volatility were measured in two separate pilot plant campaigns to capture CO₂ from flue gas under a range of absorber conditions. The laboratory data were regressed to determine NRTL binary interaction parameters that predicted the experimental points within 10 - 20%. It was proven that MEA volatility (0.45<MEA<0.55) is a viable concern in CO₂ capture processes from an economic, environmental, and overall health perspective. PZ, on the other hand, was not observed to be as volatile (0.06<PZ<0.08) as predicted by previous models and therefore volatility loss would not be a significant drawback for using it as a CO₂ capture solvent. Pilot plant results show an average MEA gas phase concentration at the absorber outlet to be approximately 45 ppm while the PZ concentrations averaged 6 ppm and 8 ppm at the absorber inlet and outlet, respectively.

Preparatory steps for the experimental investigation of the highly forbidden 5s - 6s transition in rubidium using an atom trap and laser cooling are reported. A magneto-optical trap (MOT) has been assembled including saturation spectroscopy and a dichroic vapor laser lock. A frequency-doubled diode laser system has been installed to perform the spectroscopy of the forbidden transition with cold Rb atoms in the trap. The properties of the ns - n's transition in the presence of an external electric fi#12;eld have been investigated theoretically. A fi#12;rst measurement will be exploring the Stark-induced transition amplitude and the very faint magnetic dipole amplitude. The rubidium experiment is a precursor study for a long-term project at TRIUMF, Canada's National Laboratory for nuclear and particle physics, to measure atomic parity violation in the equivalent 7s - 8s transition in francium, the heaviest alkali atom which has no stable isotopes.

No description available.

No description available.