The effect was first discovered at the University of Cologne in 1934 as a result of work on sonar. H. Frenzel and H. Schultes put an ultrasound transducer in a tank of photographic developer fluid. They hoped to speed up the development process. Instead, they noticed tiny dots on the film after developing and realized that the bubbles in the fluid were emitting light with the ultrasound turned on. It was too difficult to analyze the effect in early experiments because of the complex environment of a large number of short-lived bubbles.
In 1989 a major advancement was introduced by Felipe Gaitan and Lawrence Crum, who produced stable single-bubble sonoluminescence (SBSL). In SBSL, a single bubble, trapped in an acoustic standing wave, emits a pulse of light with each compression of the bubble within the standing wave. This technique allowed a more systematic study of the phenomenon, because it isolated the complex effects into one stable, predictable bubble. It was realized that the temperature inside the bubble was hot enough to melt steel. Interest in sonoluminescence was renewed when an inner temperature of such a bubble well above one million Kelvin was postulated. This temperature is thus far not conclusively proven, though recent experiments conducted by the University of Illinois at Urbana-Champaign indicate temperatures around 20,000 Kelvin. Research has also been carried out by Dr. Klaus Fritsch of John Carroll University, University Heights, Ohio.
The US Navy studied propeller-induced sonoluminescence during the Cold War.
Theory of Operation
Single bubble sonoluminescence (SL) is the spontaneous emission of picosecond pulses of broadband light from a micron-size gas bubble levitated in water by the application of an external sound field.The bubble expands and contracts in phase with the oscillating pressure field.
Much of the recent work on single bubble sonoluminescence has been concerned with the dynamics of the bubble motion and the detailed spectrum in the 200 to 700 nm range using a variety of gas mixtures as the contents of the sonoluminescing bubble. Recent theoretical work with shock wave focusing in the bubble has given peak temperatures up to 10^9 K, while other estimates place the peak temperature in the range of 10^4 to 10^6 K.
In 1989 a major advancement was introduced by Felipe Gaitan and Lawrence Crum, who produced stable single-bubble sonoluminescence (SBSL). In SBSL, a single bubble, trapped in an acoustic standing wave, emits a pulse of light with each compression of the bubble within the standing wave. This technique allowed a more systematic study of the phenomenon, because it isolated the complex effects into one stable, predictable bubble. It was realized that the temperature inside the bubble was hot enough to melt steel. Interest in sonoluminescence was renewed when an inner temperature of such a bubble well above one million Kelvin was postulated. This temperature is thus far not conclusively proven, though recent experiments conducted by the University of Illinois at Urbana-Champaign indicate temperatures around 20,000 Kelvin. Research has also been carried out by Dr. Klaus Fritsch of John Carroll University, University Heights, Ohio.
The US Navy studied propeller-induced sonoluminescence during the Cold War.
Theory of Operation
Single bubble sonoluminescence (SL) is the spontaneous emission of picosecond pulses of broadband light from a micron-size gas bubble levitated in water by the application of an external sound field.The bubble expands and contracts in phase with the oscillating pressure field.
Much of the recent work on single bubble sonoluminescence has been concerned with the dynamics of the bubble motion and the detailed spectrum in the 200 to 700 nm range using a variety of gas mixtures as the contents of the sonoluminescing bubble. Recent theoretical work with shock wave focusing in the bubble has given peak temperatures up to 10^9 K, while other estimates place the peak temperature in the range of 10^4 to 10^6 K.
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