EFFECT OF NOBLE-GAS DOPING IN SINGLE-BUBBLE SONOLUMINESCENCE

The trillionfold concentration of sound energy by a trapped gas bubble , so as to emit picosecond flashes of ultraviolet light, is found to b e extremely sensitive to doping with a noble gas. Increasing the noble gas content of a nitrogen bubble to about 1% dramatically stabilizes the bubble motion and increases the light emission by over an order of magnitude to a value that exceeds the sonoluminescence of either gas alone. The spectrum also strongly depends on the nature of the gas ins ide the bubble: Xenon yields a spectral peak at about 300 nanometers, whereas the helium spectrum is so strongly ultraviolet that its peak i s obscured by the cutoff of water.