Chemical Generation of Acoustic Waves: A Giant Photoacoustic Effect

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Science  10 Nov 1995:
Vol. 270, Issue 5238, pp. 963-966
DOI: 10.1126/science.270.5238.963


An anomalous photoacoustic effect is produced when a suspension of carbon particles in water is irradiated by a high-power, pulsed laser. The photoacoustic effect has an amplitude on the order of 2000 times that produced by a dye solution with an equivalent absorption coefficient and gives a distinctly audible sound above an uncovered cell. Transient grating experiments with carbon suspensions show a doubling of the acoustic frequency corresponding to the optical fringe spacing of the grating. The effect is thought to originate in high-temperature chemical reactions between the surface carbon and the surrounding water.