Mean acoustic cavitation bubble temperatures have been measured in a series of aqueous solutions containing C(1)-C(5) aliphatic alcohols, at 355 kHz. The method relies on the distribution of hydrocarbon product yields produced from the recombination of methyl radicals generated on the thermal decomposition of the alcohols. The mean bubble temperature was found to decrease with increasing concentration of alcohol with the effect being more pronounced the higher the molecular weight (the lower the vapour pressure) of the alcohol. It is shown that the decrease in the temperatures measured correlates very well with an increase in the surface excess of the alcohol, similar to that previously reported for the quenching of sonoluminescence in aqueous solutions containing alcohols [J. Phys. Chem. B 101 (1997) 10845; J. Phys. Chem. B 103 (1999) 9231]. The measured temperatures ranged from 4600+/-200 K at zero alcohol concentration to 2300+/-200 K at 0.5 M t-butanol. The validity of the method is discussed and it is concluded that even though a number of assumptions need to be applied the results appear to indicate that the method gives an accurate measure of the mean bubble temperature.

Quantitative studies of the correlation between sonochemical activity and acoustical noise spectra have been performed. The width of the second harmonic (fwhm2) of the acoustical signal in the frequency domain shows a sensitive dependence to the presence of small amounts (mM range) of an anionic surfactant in water. This sensitive dependence is also observed for other characteristics of the cavitation noise spectrum and in the sonochemical production of peroxides and correlates well with the sonoluminescence intensity observed by other researchers. Analysis of the experimental data shows that SDS probably modifies the coalescence phenomena.

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