Sonoluminescence is Chemical in Nature

Sonoluminescence is chemical in nature, not nuclear. A new experiment at the University of Illinois relieves some of the mystery previously hanging around sonoluminescence, the conversion of ultrasonic waves into picosecond light pulses via the rapid oscillations (cavitation) of bubbles in a liquid. Yuri Didenko and Kenneth Suslick assert that the intense sound compresses the bubble, increasing temperatures to such a level (10-20,000 K) that many gas molecules in the bubble would be ionized and a furious session of chemical reactions initiated. Studying the ultrasound effects on a single bubble of air in a bath of water, the researchers carefully monitored the reactant products, mostly nitrite ions (NO₂), hydroxyl radicals (OH), and light. How then is the incoming sonic energy allocated? The larger part seems to go into chemical reactions with a much smaller portion being converted to light, leaving very little for the kind of nuclear fusion reactions reported earlier this year by scientists at Oak Ridge. (Didenko and Suslick, Nature, 25 July 2002.)