Our understanding of the chemical effects of high-intensity ultrasonic irradiation of liquids is still quite limited. It is generally accepted that sonochemistry results from acoustic cavitation: the creation, growth, and implosive collapse of bubbles in ultrasonically irradiated liquids1. The mechanism of sonoluminescence in aqueous systems has been a matter of some dispute; recent discussions have suggested at least three possible origins: black-body emission2, chemiluminescence from radical recombination3, and electric discharge4. Few studies of non-aqueous sonoluminescence, however, have been conducted5-7. We present here the first spectrally resolved sonoluminescence spectra from hydrocarbon and halocarbon liquids. These spectra originate unambiguously from excited-state molecules created during acoustic cavitation. These high-energy species probably result from the recombination of radical and atomic species generated during the high temperatures and pressures of cavitation.
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