Sonoluminescence
About the experiment
Sonoluminescence is a phenomenon in which such a trapped bubble collapses under pressure and emits a pulse of visible light. As the name implies this experiment connects sound with light emissions. There is currently no widely accepted explanation of this phenomenon.
Ultrasonic waves are applied to partially-degassed water in a small transparent tank under resonance conditions. With a resonant standing wave in a tank of water, pressure forces can become sufficient to trap a gas bubble at an antinode of the standing wave. A current-pulse-heated filament generates vapor bubbles in the water that become trapped at the anti-nodes of the sound wave. At the antinodes, when the sound pressure rises toward a maximum, the bubble can collapse violently emitting a pulse of light in the process!
There are all sorts of interesting experiments for you to try. For example, using a photomultiplier tube, you can determine the time duration of the pulse of light, at what time during the period of the sound wave the flash occurs and how the light intensity varies with temperature. You can also scatter laser light off the trapped bubble to estimate its size as a function of time. Finally, you can add a noble gas to the trapped air bubble and see what happens.
What you will learn
Preparation
Required reading:
Recommended reading:
Supplementary materials
References:
- D. Lohse, Cavitation Hots Up, Nature 434, 33 (2005).
- R.J. Hiller et al., Effect of Noble Gas Doping in Single-Bubble Sonoluminescence, Science 266, 248 (1994).
- T.J. Matula and L.A. Crum, Evidence for Gas Exchange in Single-Bubble Sonoluminescence, Phys. Rev. Lett. 80, 865 (1998)
Instruments:
