Thomas J. Matula
Ronald A. Roy
Pierre D. Mourad
Appl. Phys. Lab., Univ. of Washington, Seattle, WA 98105
Recent studies involving sonoluminescence have focused on the properties and behavior of single bubbles in isolation. Some properties of single-bubble sonoluminescence (SBSL) appear to conflict with well-known properties of sonoluminescence from cavitation fields (MBSL). Direct comparisons between MBSL and SBSL have been difficult due to the difficulty in generating SBSL in nonaqueous solutions. A recent study comparing MBSL and SBSL [T. J. Matula et al., J. Acoust. Soc. Am. 96, 3252(A) (1994)] has shown that aqueous solutions of nonvolatile solutes show distinct differences in the corresponding spectra. The differences are attributed to differences in the relative symmetry of collapse of bubbles in cavitation fields versus in isolation. As part of the ongoing study to compare MBSL and SBSL, measurements were made of the apparent flash width of sonoluminescence from cavitation fields. Various well-defined cavitation regions were studied and compared to SBSL flash widths using an identical PMT for both cases. Both invasive and noninvasive mechanisms for generating MBSL were studied to determine the relative influence of ultrasonic horn immersion. Progress toward identifying the similarities and dissimilarities between MBSL and SBSL should lead to an improved understanding of sonochemical reactions. [Work supported by ONR.]