Comparison of the effects of water-soluble solutes on multibubble sonoluminescence generated in aqueous solutions by 20-and 515-kHz pulsed ultrasound

The influence of aliphatic alcohols, sodium dodecyl sulfate and sodium chloride on the intensity of sonoluminescence (SL) generated by 3.5-ms pulses of 20-kHz and 515-kHz ultrasound in air-saturated aqueous solutions has been examined. The water-soluble solutes were found to affect the SL quite differently at the two frequencies when applied at approximately the same range of power. At 20 kHz, the solutes had only a small effect on the SL signal generated, whereas at 515 kHz, the effect observed depended strongly on the specific solute present in solution. The contrasting results obtained at the two ultrasound frequencies have been interpreted in terms of transient bubbles giving rise to the SL at 20 kHz and repetitive transient bubbles producing the SL at 515 kHz.