Phase diagrams for sonoluminescing bubbles: A comparison between experiment and theory

Phase diagrams for single bubble sonoluminescence ~SBSL! are calculated. The employed model is based on a set of ordinary differential equations and accounts for the bubble hydrodynamics, heat exchange, phase change of water vapor, chemical reactions of the various gaseous species in the bubble (N2, O2, and H2O being the most important among these!, and diffusion/dissolution of the\ud reaction products in the liquid. The results of the model are compared in detail to various phase diagram data from recent experimental work, among which are air-water systems as well as systems with a xenon-nitrogen mixture as the saturated gas. Excellent quantitative agreement is found for all considered cases. Moreover, we find that the onset of SBSL is hysteretic. When starting with air typical temperatures before onset are 5500 and 15 000 K thereafter. In the light emitting regime the\ud bubbles are found to nearly entirely consist of argon

Viscosity Destabilizes Sonoluminescing Bubbles

In single-bubble sonoluminescence (SBSL) microbubbles are trapped in a standing sound wave, typically in water or water-glycerol mixtures. However, in viscous liquids such as glycol, methylformamide, or sulphuric acid it is not possible to trap the bubble in a stable position. This is very peculiar as larger viscosity normally stabilizes the dynamics. Suslick and co-workers call this new mysterious state of SBSL "moving-SBSL." We identify the history force (a force nonlocal in time) as the origin of this destabilization and show that the instability is parametric. A force balance model quantitatively accounts for the observed quasiperiodic bubble trajectories

Suppressing dissociation in sonoluminescing bubbles: The effect of excluded volume

Recent theoretical work in single-bubble sonoluminescence has suggested that water vapor in the collapsing bubble leads to energy-consuming chemical reactions, restricting the peak temperatures to values for which hardly any light emission could occur. Analyzing the reaction thermodynamics within the dense, collapsed bubble, we demonstrate that the excluded volume of the nonideal gas results in pronounced suppression of the particle-producing endothermic reactions. Thus, sufficiently high temperatures for considerable bremsstrahlung emission can be achieved