Research at the University of Illinois points to a chemical nature for sonoluminescence, the phenomenon whereby ultrasound is converted into picosecond light pulses via the rapid oscillations of bubbles in a liquid. Earlier this year, scientists at the US Oak Ridge National Laboratory raised the possibility that sonoluminescence might be linked to nuclear fusion (CERN Courier May). However, the Illinois team has found that intense sound can compress bubbles in a liquid, increasing their temperature to 10-20,000 K. This is high enough for the gas molecules inside to become ionized, and results in a series of chemical reactions. Studies on a single bubble of air in water revealed reactant products of nitrite ions, hydroxyl radicals and light. The sonic energy largely goes into chemical reactions, with a small fraction resulting in light, leaving precious little to generate nuclear fusion.
AIP Physics News Update 599
CERN Courier
Oct 1, 2002