With the increasing production of natural gas as a result of the advancement in the technology, methane conversion to more valuable products has become a must. One of the most attractive processes which allow the utilization of the world’s most abundant hydrocarbon is the oxidative coupling. The main advantage of this process is the ability of converting methane into higher paraffins and olefins (primarily C2) in a direct way using a single reactor. Nevertheless, low C2+ yields have prevented the process to be commercialized despite the fact that great number of attempts to prepare catalysts were conducted so that it can be economically viable. Due to these limitations, understanding the mechanism and kinetics of the reaction can be utilized in improving the catalysts’ performance. The reaction involves the formation of methyl radicals that undergo gas-phase radical reactions. CH4 activation is believed to be done the surface oxygen species. However, recent studies showed that, in addition to the surface oxygen mediated pathway, an OH radical mediated pathway have a large contribution on the CH4 activation. The experiments of Li/MgO, Sr/La2O3 and NaWO4/SiO2 catalysts revealed variation of behavior in activity and selectivity. In addition, water effect analysis showed that Li/MgO deactivate at the presence of water due to sintering phenomena and the loss of active sites. On the other hand, negative effect on the C2 yield and CH4 conversion rate was observed with Sr/La2O3 with increasing the water partial pressure. Na2WO4/SiO2 showed a positive behavior with water in terms of CH4 conversion and C2 yield. In addition, the increment in CH4 conversion rate was found to be proportional with PO2 ¼ PH2O ½ which is consistent with the formation of OH radicals and the OH-mediated pathway. Experiments of using ring-dye laser, which is used to detect OH in combustion experiments, were tried in order to detect OH radicals in the gas-phase of the catalyst. Nevertheless, noisy signals were obtained that prevented the ability of detecting OH at the expected few ppms concentrations. Further optimization of the experimental setup is required.

Foi construído um Laser de Corante em Anel bombeado por um laser de Argônio. Um sistema passivo de estabilização eletrônica permite a varredura sem saltos de modo, mas não reduz a largura de linha efetiva (40 MHz) devida a vibrações e flutuações na espessura do jato de corante. Um sistema ativo de estabilização está sendo implantado com a finalidade de reduzir a largura de linha obtida de pelo menos uma ordem de grandeza e aumentar a estabilidade em freqüência. A potência monomodo obtida com Rhodamina 6G é de 500 mW para 4W de bombeio. / An Argon pumped Ring Dye Laser was built. A passive stabilization system prevents mode hops during scans, but does not reduce the effective laser emission bandwidth (40 MHz) due to mechanical and acoustical jitter. An active stabilization system is being implemented to reduce the bandwidth to at least 4 MHz and to improve the frequency stability. The single mode output power obtained with Rhodamine 6G is about 500 mW to 4W pumping.

Foi construído um Laser de Corante em Anel bombeado por um laser de Argônio. Um sistema passivo de estabilização eletrônica permite a varredura sem saltos de modo, mas não reduz a largura de linha efetiva (40 MHz) devida a vibrações e flutuações na espessura do jato de corante. Um sistema ativo de estabilização está sendo implantado com a finalidade de reduzir a largura de linha obtida de pelo menos uma ordem de grandeza e aumentar a estabilidade em freqüência. A potência monomodo obtida com Rhodamina 6G é de 500 mW para 4W de bombeio. / An Argon pumped Ring Dye Laser was built. A passive stabilization system prevents mode hops during scans, but does not reduce the effective laser emission bandwidth (40 MHz) due to mechanical and acoustical jitter. An active stabilization system is being implemented to reduce the bandwidth to at least 4 MHz and to improve the frequency stability. The single mode output power obtained with Rhodamine 6G is about 500 mW to 4W pumping.

Since Feynman's realization of using quantum systems to investigate quantum dynamics, interest in creating controllable quantum systems to simulate condensed matter phenomenon has been high. With the realization of BECs in 1995, the realization of a relatively clean testbed for simulating some of these phenomenon became a reality. My PhD research has been an exploration of the production and use of Bose-Einstein Condensates for the study of superfluidity. The first 3 years have been spent in the actual building of a Na BEC apparatus. During this time, we’ve implemented a distinct technique to trap ultra cold Na atoms, i.e. the Optically Plugged Trap. In the process, we have shown how atoms in a linear trap can show spin metastability and thus maintain a nonequilibrium state for long periods of time. In studying the interaction of ultra-cold atoms with light, we have developed a technique to measure the velocity distribution of atoms using a standing optical wave (Bragg Spectroscopy). Alongside this, we have also created optical traps for atoms in which we can change to shape of the trap itself to probe different condensed matter systems. The eventual goal being the investigation of condensed matter physics, specifically superfluidity, using ultra-cold atoms.