Sonoluminescence spectra

The spectra of picosecond sonoluminescence were measured with two separate instruments (a spectrometer/CCD detector system and a scanning monochrometer/PMT detector system) for bubbles levitated in water and in glycerin/water mixtures. Results of measurements made with the scanning monochrometer/PMT detector system, which required 10 to 15 min to acquire a complete spectrum, agree favorably with those published previously by Hiller etal. [Phys. Rev. Lett. 69, 1182 (1992)]. However, measurements made with the spectrometer/CCD detector system, which required approximately 30 s, indicate that the spectrum continually changes over this time scale, with no apparent changes in the input parameters. [This work was supported in part by the Defense Nuclear Agency and the Office of Naval Research. Portions of this work were performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under Contract number W-7405-ENG-48.]