The temperature-dependence (20-300K) of the far-infrared spectrum (20-1000cm⁻¹) of Trimethylammonium Iodide Tetracyanoquinodimethane (TMA)(I)(TCNQ) in its ordered phase, has been measured for the first time. Our measurments confirmed the existence of two phase transitions near 150 and 100K. At least three absorption bands are activated below the 150K phase transition. We have assigned two of them to the totally symmetric mode Ag⁹ and Ag¹⁰ of the TCNQ molecule. We have also observed evidence of Brillouin zone splitting, where one band above 150K, split into three, below 150K. Since the conduction band of (TMA)(I)(TCNQ) is 1/3 filled, we have interpreted this result as suggesting that the 150K transition is a Peierls distortion. We also observe a sharp increased in infrared absorption at 365cm⁻¹ and a weaker one at 100cm⁻¹. Since the D.C. conductivity measurments indicates that a 1000cm⁻¹ band gap is present at all temperatures, we interpret these absorption "edges" in terms of transitions between localised states in the band gap. These localised states would be introduced by either chemical impurities or by some randomness in the potential at each TCNQ site. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

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Dissociation of gas hydrates has been the primary concern of the oil and gas industry for flow assurance, mainly in an offshore environment. There is also a growing interest in the rapid formation of gas hydrates for gas storage, transport of natural gas and carbon sequestration. In this thesis, we experimentally measure the kinetics of formation and dissociation of methane hydrates and the effect of various anionic and cationic surfactants such as sodium dodecyl sulfate (SDS), cetyl trimethylammonium bromide (CTAB) and alpha olefin sulfonate (AOS) on the association/dissociation rate constants. The importance and necessity of micelle formation in these surfactants has been studied. The effect of foam generation on the rate of formation of these hydrates has also been measured. SDS was found to significantly decrease the induction time for hydrate formation. There was an added decrease in the induction time when a foamed mixture of water and SDS was used. On the other hand CTAB and AOS had an inhibiting effect. The contribution of micelles towards promoting hydrate formation was demonstrated with a series of experiments using SDS. The micelles formed by these surfactants appear to serve as nucleation sites for the association of hydrates. New experimental data is presented to show that some surfactants and the use of foam can significantly increase the rate of hydrate formation. Other surfactants are shown to act as inhibitors. A new experimental setup is presented that allows us to distinguish between surfactants that act as promoters and inhibitors for hydrate formation. / text