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Articles 61 - 66 of 66

Full-Text Articles in Physical Chemistry

Colloidal Synthesis And Optical Characterizations Of Semiconductor Nanocrystals From Nontoxic Elements, Minh Q. Ho Jan 2015

Colloidal Synthesis And Optical Characterizations Of Semiconductor Nanocrystals From Nontoxic Elements, Minh Q. Ho

Theses and Dissertations

To date, the search efforts have shifted from the toxic II-VI, III-V and IV-VI semiconductors to more environmentally friendly materials. Among Group II-V semiconductors, Zn3P2 has shown to be a more benign option, similar to Group IV (Ge, Si) materials, for future applications in photovoltaics and optoelectronics. This work is dedicated to the development of wet-chemical synthetic routes of (1) Zn3P2 and (2) Group IV (Ge, Si, Si1-xGex) nanocrystals with precise control over composition, crystal structure, size and dispersity by adjusting different reaction parameters such as temperature, time and solvent …


Ab-Initio Study Of H2 Adsorption Upon The 001, 110, And 100 Surface Of Magnesium, Thomas F. Armstrong May 2014

Ab-Initio Study Of H2 Adsorption Upon The 001, 110, And 100 Surface Of Magnesium, Thomas F. Armstrong

Theses and Dissertations

Until recently, the only pathway for H2 adsorption onto conventional magnesium thin films was the [001] surface. With the discovery of Mg nanoblade/nanotree fabrication, there are now multiple surfaces for adsorption. A keen understanding of each surface's hydrogen adsorption kinetics is a key part of deciding if these surfaces present a more attractive hydrogen storage material than conventional thin films. This study focused on the use of ab-initio methods to compare the adsorption of H2 molecules onto the [001], [100], and [110] surfaces as well as an analysis of hybrid functionals and their advantages over traditional functionals for minimum energy …


Organic-Inorganic Hybrid Nanostructures For Solar Cell Applications, Samir Mahdi Abdulalmohsin May 2014

Organic-Inorganic Hybrid Nanostructures For Solar Cell Applications, Samir Mahdi Abdulalmohsin

Theses and Dissertations

The enticing electro-optical properties of nanostructured materials such as carbon nanotubes, graphene, CdS nanocrystals and ZnO nanowrie bring new vigor into the innovation of photovoltaics. The main purpose of this dissertation is to develop novel nano-structured materials for low cost solar cell applications. Fabrication, characterization, and solar cell application of organic-inorganic hybrid structures are the main focus of this research. Polyaniline (PANI)/multi-walled carbon nanotube (MWNT) composite films were synthesized by an electrochemical polymerization of aniline with airbrushed MWNTs on ITO substrates. It was found that the incorporation of MWNTs in PANI effectively increase the film conductivity with a percolation threshold …


Calculation Of Collisional Cross Sections For The ²P3/2 > ²P1/2 Transition In Alkali-Noble Gas Systems, Samuel D. Butler Mar 2010

Calculation Of Collisional Cross Sections For The ²P3/2 > ²P1/2 Transition In Alkali-Noble Gas Systems, Samuel D. Butler

Theses and Dissertations

Collisional cross sections were calculated as a function of energy for two coupled one dimensional, spherically symmetric potentials. The Split Operator Method was used to propagate an initial Moller state, chosen to be a Gaussian in the asymptotic limit, through a potential. The correlation between the wave packet and Moller final state was calculated at each time step. Using the Channel Packet Method, the correlation function was used to obtain scattering matrix elements. From scattering matrix elements for several different effective potential values and using the Method of Partial Waves, the collisional cross section is calculated for the transition from …


Q-Switched And Mode Locked Short Pulses From A Diode Pumped, Yb-Doped Fiber Laser, Seth M. Swift Mar 2009

Q-Switched And Mode Locked Short Pulses From A Diode Pumped, Yb-Doped Fiber Laser, Seth M. Swift

Theses and Dissertations

A diode-pumped, ytterbium (Yb)-doped fiber laser system was designed and demonstrated to operate in continuous wave (cw), passively Q-switched and possibly passively mode locked operation. To our knowledge, this was the first fiber laser oscillator built at the Air Force Institute of Technology. A Cr4+:YAG (Chromium: Ytterbium Aluminum Garnett) crystal was used as a saturable absorber to generate Q-switched pulses. Attempts to mode lock the laser were performed using a semiconductor saturable absorber mirror (SESAM) and through nonlinear polarization rotation (NPR). The best output power result was 5 Watts (W) while pumping at 8.3 W, yielding 60% efficiency …


Electrochemical Studies Of Some Furyl, Indol, Pyrrol, Hydroxynapthyl And Thienyl Derived Sulfonamides And Their Antibacterial Activities, Raja S. Machana Jan 2007

Electrochemical Studies Of Some Furyl, Indol, Pyrrol, Hydroxynapthyl And Thienyl Derived Sulfonamides And Their Antibacterial Activities, Raja S. Machana

Theses and Dissertations

Sulfonamides are synthetic, wide-spectrum, antibiotics that find current therapeutic applications in the treatment of urinary tract infections, nocardiosis, and toxoplasmosis. Rapid development of bacterial resistance to this class of antimicrobial agents has obligated the need for synthesis of new sulfonamide derivatives. N 1 substitution with heterocyclic moieties produced variable antibacterial efficacies and their structure activity relationships were fairly established. However, para-amino (the N of which is designated as N 4 ) sulfonamide derivatives are less commonly studied. In this research we have selected a series of para-amino sulfonamide derivatives. Since redox potentials are important in determining the physiological activity of …