Acoustical stability of a sonoluminescing bubble.

In the parameter region for sonoluminescence of a single levitated bubble in a water-filled resonator it is observed that the bubble may have an enormous spatial stability leaving it "pinned" in the fluid and allowing it to emit light pulses of picosecond accuracy. We report here observations of a complex harmonic structure in the acoustic field surrounding a sonoluminescing bubble. We show that this complex sound field determines the position of the bubble and may either increase or decrease its spatial stability. The acoustic environment of the bubble is the result of the excitation of high-order normal modes of the resonator by the outgoing shock wave generated by the bubble collapse.