We review recent work on the use of sonoluminescence (SL) to probe spectroscopically the conditions created during cavitation, both in clouds of collapsing bubbles (multibubble sonoluminescence, (MBSL)) and in single bubble events. The effective MBSL temperature can be controlled by the vapor pressure of the liquid or the thermal conductivity of the dissolved gas over a range from ∼1600 to ∼9000 K. The effective pressure during MBSL is ∼300 bar, based on atomic line shifts. Given nanosecond emission times, this means that cooling rates are >1012 K/s. In sulfuric and phosphoric acid, the low volatility and high solubility of any sonolysis products make bubble collapse more efficient and evidence for an optically opaque plasma core is found.
Bibliographical noteFunding Information:
We dedicate this paper to the memory of Oleg Abramov, a great bear of a man, whose good fellowship and thoughtful approach to science we sorely miss. In 1994, Oleg and his daughter spent an extended stay in our labs in Urbana, which was a highpoint of our sonochemical research. We gratefully acknowledge the financial support of the U.S. National Science Foundation (CHE and DMR) .
- Emission temperature