Sonoluminescence initiated by laser irradiation of carbon suspensions

We report observation of sonoluminescence following irradiation of suspensions of carbon in water with a high power, pulsed laser. The mechanism for generation of a gas bubble is chemical in origin: the heating of the carbon particles by absorption of laser radiation causes the production of high pressure ${\mathrm{H}}_{\mathrm{2}}$ and CO through reaction of carbon with the water surrounding the particles. Expansion of the bubble past its equilibrium diameter results in oscillation of the bubble diameter which, several hundred μs after the initial formation of the bubble, results in emission of optical and acoustic radiation. The effects of laser power, the concentration of carbon in the suspension, dissolved Ar, and temperature on the sonoluminescent intensity are reported.