Time scales for quenching single-bubble sonoluminescence in the presence of alcohols

The rate at which single-bubble sonoluminescence is quenched in the presence of alcohol is examined. Single bubble sonoluminescence bubbles are generated in a partially degassed argon-water/alcohol mixture. Quenching rates are measured by recording the instantaneous bubble response and corresponding light emission during a sudden increase in driving pressure. The light emission intensity initially grows as the bubble settles into a steady-state. The intensity then decreases as endothermic processes begin to dominate. Quenching rates increase with the carbon chain length (C-1-C-4). Complete quenching in the presence of methanol requires over 8000 acoustic cycles, while quenching with butanol occurs in about 50 acoustic cycles (driving frequency = 22.5 kHz). These observations are consistent with the view that quenching requires the repetitive injection of alcohol molecules leading to the accumulation of (hydrocarbon) gaseous products within the bubbles.