A single bubble in water is excited by a standing ultrasound wave. At high intensity the bubble starts to emit light. Together with the emitted light pulse, a shock wave is generated in the liquid at collapse time. The time-dependent velocity of the outward-travelling shock is measured with an imaging technique. The pressure in the shock and in the bubble is shown to have a lower limit of 5500 bars. Visualization of the shock and the bubble at different phases of the acoustic cycle reveals previously unobserved dynamics during stable and unstable sonoluminescence.Comment: 4 pages, 7 figure

Single bubble sonoluminescence has been experimentally produced through a novel approach of optimized sound excitation. A driving consisting of a first and second harmonic with selected amplitudes and relative phase results in an increase of light emission compared to sinusoidal driving. We achieved a raise of the maximum photo current of up to 300% with the two-mode sound signal. Numerical simulations of multimode excitation of a single bubble are compared to this result.Comment: 4 pages, 4 figures, accepted for publication in Phys. Rev. Let

Micromanipulation of sonoluminescing bubbles is achieved by generating a complex sound field consisting of spatially distributed modes of higher harmonics of a basic driving frequency. Bubbles can be manipulated in space and shifted to any desired spot. The interaction with the complex sound field also allows for specification of the violence of a bubble collapse.

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.

In single-bubble sonoluminescence, a bubble is levitated and forced to oscillate by a standing sound wave. Once per cycle, at the maximum compression of the bubble volume, the emission of a pulse of visible light is observed; due to the strong bubble collapse, a shock wave is emitted in the liquid also. It was found that these shock waves can be visualized by the means of a schlieren method. Using a stroboscopic illumination of the bubble, its dynamical behavior and the shocks can be recorded in slow motion by a video camera. Experimentally measured velocities of the shock waves were compared with numerical calculations. Further, the recorded shock waves contain information about the bubble position and collapse time. In the regime of instable sonoluminescence, sudden changes in bubble position depending on bubble size were observed. The phenomenon in the context of interactions of the bubble with the complex sound field is discussed. [Work supported by the DFG (SFB 185).]