Spectroscopic studies of multi-bubble and single bubble sonoluminescence

The collapse of cavitating bubbles in an acoustic field subjects the bubble contents to extreme temperatures and pressures that lead to both sonochemistry and the emission of light: multi-bubble sonoluminescence (MBSL). This thesis describes a methodology capable of determining the temperature of sonoluminescence under a wide range of conditions, and thus the mechanism of heating. Sonication of volatile metal carbonyls in nonvolatile solvents leads to intense emission from the metal atoms, the spectra of which are sensitive to the temperature of emission. Fe, Mo and Cr emission resulting from the sonolysis of their parent carbonyls in silicone oil all occur at 4800 +/- 500 K.; The introduction of polyatomic gases to the bubble leads to a decrease in the temperature of sonoluminescence, consistent with the compressional heating model of cavitation. The temperature is much more sensitive to solvent vapor than to small gaseous hydrocarbons, which the author attributes to the importance of intrabubble chemistry. This hypothesis is strongly supported by the behavior of the metal atom emission with respect to the underlying continuum, which is shown to be molecular in origin. A refined model of cavitation detailing the importance of intrabubble chemistry in limiting the temperature within the bubble is presented.; Emission from metal atoms under both helium and argon revealed that the emission occurs unequivocally from a high-pressure noble gas environment within the bubble. High-resolution spectra arising from the sonication of Cr(CO)6 in argon-saturated silicone oil indicates that the pressure within the bubble at the time of emission is at least 350 bar.; Single bubble sonoluminescence (SBSL) was also studied. Small concentrations of organic solutes suppress SBSL from water containing dissolved air, but only when the solvents are volatile and can enter the bubble interior. These results were interpreted in light of the dissociation hypothesis for SBSL in water. This interpretation in turn led to the development of rationale for choosing other solvents for SBSL, a phenomenon heretofore only observed in water. Several other liquids were found to support SBSL from both spatially stable and moving bubbles and, for the first time, molecular emission was detected in SBSL spectra.