Experimental study of light emitted by spark-generated bubbles in water

The emission of light from spark-generated bubbles freely oscillating in water far from boundaries is studied experimentally. The observations concentrate on light flashes radiated at final stages of the first bubble contraction and early stages of the following bubble expansion. It is shown that the shape of the emitted light pulses is not "Gaussian", but asymmetric with a leading edge moderately growing and a trailing edge steeply decreasing. The maximum values and widths of these optical pulses are determined for bubbles having different sizes and oscillating with different intensities. The variation of the maximum values and pulse widths with bubble size and intensity of oscillation is discussed, as well as the observed weak correlation between these two quantities.