The Timing of Sonoluminescence
  We measured the timing of sonoluminescence by observing laser light scattered from a single sonoluminescing bubble. We performed this measurement on 23.5 kHz, 17.8 kHz, 13.28 kHz and 7920 Hz systems, and found that the flash typically occurs 100 nanoseconds before the minimum radius. These results motivate a new model of sonoluminescence: the flash results from the discharge of an excited cold condensate formed during the adiabatic expansion of the bubble. 
Thomas E. Brennan and Gustave C. Fralick
physics.gen-ph