Sonoluminescence: a Star in a Jar.
Rachel Romond 
Faculty Advisor: M. Wu

      Sonoluminescence is a process of turning sound into light. When a single air bubble suspended in water is driven by an appropriate acoustic signal, it emits short flashes of light. These flashes are only picoseconds long and repeat at the frequency of the driving sound, giving the appearance of a glowing bubble. Based on the wavelength of the emitted light, it has been calculated that the temperature at the very center of the glowing bubble is hotter than the surface of the sun [1]. The energy from the sound waves is focused nearly a trillionfold [2].  However, the mechanism by which the energy is focused remains unknown. In addition to this light, sonoluminescing bubbles also emit sound waves. A characterization of the emitted sound may provide some insight into the nature of its production and shed some light on the continuing enigma of sonoluminescence. The goal of this ongoing project is to measure the acoustic signal of a sonoluminescing bubble and to compare it with the driving signal in the time domain. We have designed and built the experimental apparatus, and are in the final stages of testing the acoustic driving circuit.

1. Putterman, Seth J. Sonoluminescence: Sound into Light. Scientific American, vol. 272, no. 2, p.46-51 (1995).

2. Barber, B.P.; Hiller, R.A.; Lofstedt, R.; Putterman, S.J.; Weninger, K.R. Defining the unknowns of sonoluminescence. Physics Reports, vol. 281, p. 65-143 (1997).

Support provided by: National Science Foundation-AIRE