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Georgia Tech
1.
Schaaff, T. Gregory.
Preparation and characterization of thioaurite cluster compounds.
Degree: PhD, Chemistry, 1998, Georgia Tech
URL: http://hdl.handle.net/1853/30858 
Subjects/Keywords: Crystals Structure; Transition metal compounds; Asymmetric synthesis
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APA (6th Edition):
Schaaff, T. G. (1998). Preparation and characterization of thioaurite cluster compounds. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/30858
Chicago Manual of Style (16th Edition):
Schaaff, T Gregory. “Preparation and characterization of thioaurite cluster compounds.” 1998. Doctoral Dissertation, Georgia Tech. Accessed January 26, 2021.
http://hdl.handle.net/1853/30858.
MLA Handbook (7th Edition):
Schaaff, T Gregory. “Preparation and characterization of thioaurite cluster compounds.” 1998. Web. 26 Jan 2021.
Vancouver:
Schaaff TG. Preparation and characterization of thioaurite cluster compounds. [Internet] [Doctoral dissertation]. Georgia Tech; 1998. [cited 2021 Jan 26].
Available from: http://hdl.handle.net/1853/30858.
Council of Science Editors:
Schaaff TG. Preparation and characterization of thioaurite cluster compounds. [Doctoral Dissertation]. Georgia Tech; 1998. Available from: http://hdl.handle.net/1853/30858
Georgia Tech
2.
Arredondo, Melissa Gayle.
Zero-Dimensional Magnetite.
Degree: PhD, Chemistry and Biochemistry, 2006, Georgia Tech
URL: http://hdl.handle.net/1853/14151
► Low-dimensional magnetic systems are of interest due to several new effects and modifications that occur at sizes below the average domain grain boundary within the…
(more)
▼ Low-dimensional magnetic systems are of interest due to several new effects and modifications that occur at sizes below the average domain grain boundary within the bulk material. Molecule-like magnetite (Fe3O4) nanoparticles, with sizes ranging from one to two nm were synthesized and characterized in order to investigate new properties arising from quantum size effects. These small systems will provide opportunities to investigate magnetism of zero-dimension systems. A zero-dimensional object is usually called a quantum dot or artificial atom because its electronic states are few and sharply separated in energy, resembling those within an atom. Since the surface to volume ratio is the highest for zero-dimensional systems, most of the changes to magnetic behavior will be observed in ultra-fine magnetic particles. Chemically functional magnetic nanoparticles, comprised of a Fe3O4 magnetite core encased in a thin aliphatic carboxylate, have been prepared by sequential high temperature decomposition of organometallic compounds in a coordinating solvent. In this work, aliphatic carboxylic acid chain length, reaction temperature and duration were varied to produce small core diameters. In order to correlate size effects with changes in particle formation, it is important to have a through understanding of the structural components. This includes studies of the core size, surface effects, decomposition, electronic properties and magnetic behavior. Quantum size effects were observed in the (Fe3O4)X(carboxylate)Y monolayer protected clusters (MPCs) when the average core diameter was ≤ 2.0 nm, evidenced by a blue shifted absorbance band maxima, suggesting the onset of quantum confinement. These (Fe3O4)X(carboxylate)Y MPCs also posses a complex interplay between surface and finite size effects, which govern the magnetic properties of these zero-dimensional systems. These MPCs are all superparamagnetic above their blocking temperatures with total magnetic anisotropy values greater than the bulk value due to an increase in surface and magnetocrystalline anisotropy. A non-linear decrease in saturation magnetization (MS) [Bohr Magneton] per cluster) as a function of the reciprocal of core radius have been attributed to surface effects such as a magnetically inactive layer or an increase in spin disorder as core diameter decreases. The reduced core dimensions of these MPCs make them ideal candidates for further investigation of quantum magnetic systems.
Advisors/Committee Members: Robert Whetten (Committee Chair), Lawrence Bottomley, Walt De Heer, Mostafa El-Sayed, Uzi Landman, and David Sherrill (Committee Members).
Subjects/Keywords: Quantum magnetism; Quantum size effects; Magnetite; Nanoclusters; Nanoparticles; Superparamagnetism; Anisotropy; Magnetite; Nanoparticles; Paramagnetism; Quantum biochemistry; Surface chemistry
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APA (6th Edition):
Arredondo, M. G. (2006). Zero-Dimensional Magnetite. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/14151
Chicago Manual of Style (16th Edition):
Arredondo, Melissa Gayle. “Zero-Dimensional Magnetite.” 2006. Doctoral Dissertation, Georgia Tech. Accessed January 26, 2021.
http://hdl.handle.net/1853/14151.
MLA Handbook (7th Edition):
Arredondo, Melissa Gayle. “Zero-Dimensional Magnetite.” 2006. Web. 26 Jan 2021.
Vancouver:
Arredondo MG. Zero-Dimensional Magnetite. [Internet] [Doctoral dissertation]. Georgia Tech; 2006. [cited 2021 Jan 26].
Available from: http://hdl.handle.net/1853/14151.
Council of Science Editors:
Arredondo MG. Zero-Dimensional Magnetite. [Doctoral Dissertation]. Georgia Tech; 2006. Available from: http://hdl.handle.net/1853/14151
Georgia Tech
3.
Sjostedt, Steven Jeffrey.
Investigation of Photochemistry at High Latitudes: Comparison of model predictions to measurements of short lived species.
Degree: PhD, Earth and Atmospheric Sciences, 2006, Georgia Tech
URL: http://hdl.handle.net/1853/14109
► Recent field campaigns have measured enhanced levels of NOx (NO+NO2) and HOx precursors (i.e., H2O2, CH2O, and HONO) that can not be accounted for by…
(more)
▼ Recent field campaigns have measured enhanced levels of NOx (NO+NO2) and HOx precursors (i.e., H2O2, CH2O, and HONO) that can not be accounted for by gas phase chemistry alone. Snowpack emission is now considered a source of these species. Therefore, the photochemistry in the polar boundary layer is now believed to be much more complex than initially thought.
Field campaigns to Summit, Greenland in the summer of 2003 and the spring of 2004 have obtained the first measurements of peroxy (HO2+RO2) and hydroxyl (OH) radicals in the Artic boundary layer. Measurements were collected with a chemical ionization mass spectrometer (CIMS). A highly constrained (ie., O3, H2O, CH4, CO, j-values, NO, H2O2,CH2O, and HONO) 0-D steady-state model was employed in order to test our current understanding of photochemistry. HO2+RO2 measurements were in excellent agreement with model predictions for both spring and summer. OH measurements were in good agreement with spring model predictions but were a factor of two greater than summer model predictions. The role of snowpack emission is also addressed in a HOx budget performed on the spring campaign.
Measurements of nitric acid (HNO3) and pernitric acid (HO2NO2) were obtained with the CIMS during the Antarctic Tropospheric Chemistry Investigation (ANTCI). The linkage between HOx and NOx chemistry is examined through partitioning of reactive nitrogen between HNO3 and HO2NO2. The possible impact of reactive nitrogen partitioning on nitrate ions (NO3-) at coring sites is also investigated.
Advisors/Committee Members: Dr. Greg Huey (Committee Chair), Dr. David Tan (Committee Member), Dr. Paul Wine (Committee Member), Dr. Robert Whetten (Committee Member), Dr. Rodney Weber (Committee Member).
Subjects/Keywords: Nitric acid; Pernitric acid; OH; HOx; Nitric acid; Photochemistry; Atmospheric chemistry
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APA (6th Edition):
Sjostedt, S. J. (2006). Investigation of Photochemistry at High Latitudes: Comparison of model predictions to measurements of short lived species. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/14109
Chicago Manual of Style (16th Edition):
Sjostedt, Steven Jeffrey. “Investigation of Photochemistry at High Latitudes: Comparison of model predictions to measurements of short lived species.” 2006. Doctoral Dissertation, Georgia Tech. Accessed January 26, 2021.
http://hdl.handle.net/1853/14109.
MLA Handbook (7th Edition):
Sjostedt, Steven Jeffrey. “Investigation of Photochemistry at High Latitudes: Comparison of model predictions to measurements of short lived species.” 2006. Web. 26 Jan 2021.
Vancouver:
Sjostedt SJ. Investigation of Photochemistry at High Latitudes: Comparison of model predictions to measurements of short lived species. [Internet] [Doctoral dissertation]. Georgia Tech; 2006. [cited 2021 Jan 26].
Available from: http://hdl.handle.net/1853/14109.
Council of Science Editors:
Sjostedt SJ. Investigation of Photochemistry at High Latitudes: Comparison of model predictions to measurements of short lived species. [Doctoral Dissertation]. Georgia Tech; 2006. Available from: http://hdl.handle.net/1853/14109
Georgia Tech
4.
Schill, Alexander Wilhem.
Interesting Electronic and Dynamic Properties of Quantum Dot Quantum Wells and other Semiconductor Nanocrystal Heterostructures.
Degree: PhD, Chemistry and Biochemistry, 2006, Georgia Tech
URL: http://hdl.handle.net/1853/11514
► Some interesting electronic and dynamic properties of semiconductor nanocrystal heterostructures have been investigated using various spectroscopic methods. Semiconductor nanocrystal heterostructures were prepared using colloidal synthesis…
(more)
▼ Some interesting electronic and dynamic properties of semiconductor nanocrystal heterostructures have been investigated using various spectroscopic methods. Semiconductor nanocrystal heterostructures were prepared using colloidal synthesis techniques. Ultrafast transient absorption spectroscopy was used to monitor the relaxation of hot electrons in CdS/HgS/CdS quantum dot quantum wells. Careful analysis of the hot electron relaxation in CdS/HgS/CdS quantum dot quantum wells reveals an energy dependent relaxation mechanism involving electronic states of varying CdS and HgS composition. The composition of the electronic states, combined with the layered structure of the nanocrystal permits the assignment of CdS localized and HgS localized excited states. The dynamic effect of surface passivation is then shown to have the strongest influence on excited states that are localized in the HgS layer.
New quantum dot quantum well heterostructures of different sizes and compositions were also prepared and studied. The dynamic properties of CdS/CdSe/CdS colloidal quantum wells suggest simultaneous relaxation of excited electrons within the CdS core and CdSe shell on the sub-picosecond time scale. Despite the very different electronic structure of CdS/CdSe/CdS compared to CdS/HgS/CdS, the time scales of the relaxation and electron localization were very similar.
Enhancement of trap luminescence was observed when CdS quantum dots were coated with silver. The mechanism of the enhancement was investigated using time-resolved spectroscopic techniques.
Advisors/Committee Members: Mostafa El-Sayed (Committee Chair), John Zhang (Committee Member), Phillip First (Committee Member), Robert Whetten (Committee Member), Thomas Orlando (Committee Member).
Subjects/Keywords: Ultrafast; Hot electron relaxation; Colloids; Nanoparticles; Femtosecond; Charge transfer; Semiconductor nanocrystals; Quantum wells; Quantum dots; Nanocrystals Electric properties
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APA ·
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APA (6th Edition):
Schill, A. W. (2006). Interesting Electronic and Dynamic Properties of Quantum Dot Quantum Wells and other Semiconductor Nanocrystal Heterostructures. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/11514
Chicago Manual of Style (16th Edition):
Schill, Alexander Wilhem. “Interesting Electronic and Dynamic Properties of Quantum Dot Quantum Wells and other Semiconductor Nanocrystal Heterostructures.” 2006. Doctoral Dissertation, Georgia Tech. Accessed January 26, 2021.
http://hdl.handle.net/1853/11514.
MLA Handbook (7th Edition):
Schill, Alexander Wilhem. “Interesting Electronic and Dynamic Properties of Quantum Dot Quantum Wells and other Semiconductor Nanocrystal Heterostructures.” 2006. Web. 26 Jan 2021.
Vancouver:
Schill AW. Interesting Electronic and Dynamic Properties of Quantum Dot Quantum Wells and other Semiconductor Nanocrystal Heterostructures. [Internet] [Doctoral dissertation]. Georgia Tech; 2006. [cited 2021 Jan 26].
Available from: http://hdl.handle.net/1853/11514.
Council of Science Editors:
Schill AW. Interesting Electronic and Dynamic Properties of Quantum Dot Quantum Wells and other Semiconductor Nanocrystal Heterostructures. [Doctoral Dissertation]. Georgia Tech; 2006. Available from: http://hdl.handle.net/1853/11514
Georgia Tech
5.
Barber, Jabulani Randall Timothy.
Mechanical compression of coiled carbon nanotubes.
Degree: PhD, Chemistry and Biochemistry, 2009, Georgia Tech
URL: http://hdl.handle.net/1853/28216
► Carbon nanotubes are molecular-scale tubes of graphitic carbon that possess many unique properties. They have high tensile strength and elastic modulus, are thermally and electrically…
(more)
▼ Carbon nanotubes are molecular-scale tubes of graphitic carbon that possess many unique properties. They have high tensile strength and elastic modulus, are thermally and electrically conductive, and can be structurally modified using well established carbon chemistries. There is global interest in taking advantage of their unique combination of properties and using these interesting materials as components in nanoscale devices and composite materials.
The goal of this research was the correlation of the mechanical properties of coiled carbon nanotubes with their chemical structure. Individual nanocoils, grown by chemical vapor deposition, were attached to scanning probe tip using the arc discharge method. Using a scanning probe microscope the nanocoils are repeatedly brought into and out of contact with a chemically-modified substrate. Precise control over the length (or area) of contact with the substrate is achievable through simultaneous monitoring the cantilever deflection resonance, and correlating these with scanner movement. The mechanical response of nanocoils depended upon the extent of their compression. Nonlinear response of the nanocoil was observed consistent with compression, buckling, and slip-stick motion of the nanocoil. The chemical structure of the nanocoil and its orientation on the tip was determined using scanning and transmission electron microscopy.
The mechanical stiffness of eighteen different nanocoils was determined in three ways. In the first, the spring constant of each nanocoil was computed from the slope of the linear response region of the force-distance curve. The assumptions upon which this calculation is based are: 1) under compression, the cantilever-nanocoil system can be modeled as two-springs in series, and 2) the nanocoil behaves as an ideal spring as the load from the cantilever is applied. Nanocoil spring constants determined in this fashion ranged from 6.5x10-3 to 5.16 TPa for the CCNTs understudy. In the second, the spring constant of the nanocoil was computed from measuring the critical force required to buckle the nanocoil. The critical force method measured the force at the point where the nanocoil-cantilever system diverges from a linear region in the force curve. Nanocoil spring constants determined in this fashion ranged from 1.3x10-5 to 10.4 TPa for the CCNTs understudy. In the third, the spring constant of each nanocoil was computed from the thermal resonance of the cantilever-nanocoil system. Prior to contact of the nanocoil with the substrate, the effective spring constant of the system is essentially that of the cantilever. At the point of contact and prior to buckling or slip-stick motion, the effective spring constant of the system is modeled as two springs in parallel. Nanocoil spring constants determined in this fashion ranged from 2.7x10-3 to 0.03 TPa for the CCNTs understudy.
Using the thermal resonance of the cantilever system a trend was observed relating nanocoil structure to the calculated modulus. Hollow, tube-like…
Advisors/Committee Members: Lawrence Bottomley (Committee Chair), Aldo Ferri (Committee Member), E. Kent Barefield (Committee Member), Levent Degertekin (Committee Member), Robert Whetten (Committee Member), Satish Kumar (Committee Member), Zhong Lin Wang (Committee Member).
Subjects/Keywords: Slip-stick; Tribology; Thermal resonance spectrum; Mechanical properties; Force spectroscopy; Atomic force microscopy; Nanocoil; Multi-walled carbon nanotube; Nanospring; Nanotube; Nanotubes Mechanical properties; Carbon; Chemical structure; Springs (Mechanism)
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APA (6th Edition):
Barber, J. R. T. (2009). Mechanical compression of coiled carbon nanotubes. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/28216
Chicago Manual of Style (16th Edition):
Barber, Jabulani Randall Timothy. “Mechanical compression of coiled carbon nanotubes.” 2009. Doctoral Dissertation, Georgia Tech. Accessed January 26, 2021.
http://hdl.handle.net/1853/28216.
MLA Handbook (7th Edition):
Barber, Jabulani Randall Timothy. “Mechanical compression of coiled carbon nanotubes.” 2009. Web. 26 Jan 2021.
Vancouver:
Barber JRT. Mechanical compression of coiled carbon nanotubes. [Internet] [Doctoral dissertation]. Georgia Tech; 2009. [cited 2021 Jan 26].
Available from: http://hdl.handle.net/1853/28216.
Council of Science Editors:
Barber JRT. Mechanical compression of coiled carbon nanotubes. [Doctoral Dissertation]. Georgia Tech; 2009. Available from: http://hdl.handle.net/1853/28216
. 
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