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Many clusters of galaxies contain large quantities of hot diffuse gas. I have studied the properties of waves in this gas using Lagrangian perturbations. The gas is far more thermally stable than is commonly thought. For bremsstrahlung cooling, all modes that remain oscillatory are damped. Galaxy motions, especially the oscillations of a central cD galaxy, are an important way of generating large amplitude waves in cluster gas. This is especially pertinent in view of the growing realization that cD galaxies are not at rest with respect to the cluster. I also present evidence that weak magnetic fields tangled on scales of ~ 10 kpc are common in cluster gas. Electrons responsible for the flow of heat in the gas must travel along the field lines, leading to a global reduction in heat flux. The superposition of many different field lines implies that the cluster gas is a multiphase medium. Such a picture has been suggested independently by the claimed observation of mass drop-out from cooling flows. I also show some results from a more advanced study using real magnetic fields rather than random walk models.

Laser Induced Fluorescence has been used to study rotational and vibrational energy disposal following gas phase photodissociations and reactions of small molecules. Three distinct systems have been studied. The rotational and vibrational distributions in the ground and first electronically excited states of the OH radical have been studied following the two and three photon dissociation of water using laser radiation of 266nm and 355nm wavelength respectively. The results have been compared to recent theoretical calculations and experimental investigations at different wavelengths in the same region of the spectrum. The rotational distribution in vibrational levels of the ground electronic state of the NO molecule following 355nm photodissociation of methyl nitrite have been studied and compared to recent experimental studies of the photodissociation of NO containing molecules. A statistical treatment allowed the vibrational distribution to be determined. A simple model is described which rationalises the process. Finally, the rotational distributions within vibrational levels of the ground electronic state of the CO molecule, produced via the gas phase reaction between oxygen atoms and the CS radical, are presented. The vibrational distribution resulting from this reaction is well established but, to date, there have been no reports of the rotational distribution. A proposal has been made to employ the system studied in a vacuum ultra violet laser. Some comments are made concerning this proposal.

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references and index.

Thesis (Ph.D.) - University of Queensland, 2005. / Includes bibliography.

Thesis (Ph. D.)--University of Chicago, Department of Physics, December 2002. / Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1975. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.

Thesis (Ph. D.)--Lehigh University, 2006. / Includes vita. Includes bibliographical references (leaves 169-172).