Effect of alcohol on single-bubble sonoluminescence.

The driving parametric regions in frequency-amplitude space and the optimal parameters for single-bubble sonoluminescence (SBSL) in alcohol aqueous solutions are studied systematically by taking measurements of the spectrum and bubble dynamics. The experimental results show that with an increase in alcohol concentration, the region shrinks and shifts. The optimized parameters differ for alcohol solutions having different concentrations, and SBSL driven by fixed parameters dims quickly and is even destroyed immediately with the addition of a small amount of alcohol to pure water. Furthermore, it is seen that the intensity of optimized SBSL decreases as the alcohol concentration increases. The corresponding measurements of the dynamics of the optimized SBSL bubble show that the maximum bubble radius at an alcohol concentration of 1.04 mM is only half that for pure water. Meanwhile, the optimized driving amplitude acquired by direct measurement and that obtained by fitting the radius-time curves with the Rayleigh-Plesset equation both decrease by 12% in the same comparison. Therefore, a decrease in the driving acoustic pressure may be an important reason for the decrease in the optimized SBSL intensity, which should help clarify SBSL mechanisms in alcohol aqueous solutions.