Sonoluminescence from non-aqueous liquids.
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 liquids. 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 emission, chemiluminescence from radical recombination, and electric discharge. Few studies of non-aqueous sonoluminescence, however, have been conducted. 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.