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Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 39-41). Also available via the Internet.

Thesis--University of Florida. / Description based on print version record. Typescript. Vita. Includes bibliographical references.

Thesis (M.S.)--Montana State University--Bozeman, 2005. / Typescript. Chairperson, Graduate Committee: David Dickensheets. Includes bibliographical references (leaves 65-66).

The formation of a laser-driven shock in fused silica was observed experimentally. Fused silica slabs were irradiated with 0.53 /µm laser light in a pulse of 2 ns FWHM at intensities ranging from 10¹² W/cm² to 5 x 10¹³ W/cm², producing a pressure pulse ranging from < 30 GPa to 500 GPa. Shock trajectories were observed using streaked shadowgram and schlieren methods. The experiment was modelled with a one-dimensional Lagrangean laser-plasma hydrocode. Comparison of the simulation results with the experimental observations indicate that the high pressure shock develops anomalously slowly at intensities > 1 x 10¹³ W/cm². Furthermore the shock displayed non-steady propagation for a transient period following its formation. The non-steady propagation is interpreted to be due to a relaxation process in the phase transformation of the fused silica to the high pressure stishovite phase which occurs in the shock front. The slow formation of the shock at high intensities is consistent with a significant volume collapse (phase transition) possibly induced by isentropic compression; however, this interpretation is uncertain due to the complications introduced by non-equilibrium thermodynamics and the possibility of two-dimensional motion. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The activity and wettability of raw fused silica capillary tubing was found to be widely variable which places severe limitations on the reproducibility of column deactivation and inertness. Hydrothermal treatment of the raw fused silica with nitric acid was proven to be very effective for cleaning and maximizing the degree of silanol coverage of the surface. The capillary rise method was used to obtain contact angle data for untreated fused silica and fused silica treated with a variety of deactivating reagents. This contact angle data was used in the construction of Zisman plots which allowed quantitative comparison of the wettability and degree of surface coverage obtained with the different deactivants. The thermal stability of the final column was related to the success of the deactivation procedure. The choice of cross-linking initiator was also found to have an affect on column inertness. In the synthesis of intermediate polarity polysiloxane stationary phases, mixtures of commercially available cyclic siloxanes were shown to be a viable alternative to the use of dichlorosilanes as starting material. The main advantages were the simplification of the synthesis procedure, simpler and better molecular weight control of the polymer, and the elimination of HC1 as a by-product of both the polymerization and endcapping steps. A new stationary phase, 7% cyanoethyl, 7% phenyl, 1% vinyl, methyl polysiloxane was synthesized and found to be more polar than OV-1701 with higher temperature stability, easily cross-linked, and suitable for use in supercritical fluid chromatography. / Ph. D.

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