SINGLE-BUBBLE SONOLUMINESCENCE. Fernando Enrique
Ziegler, The University of Texas at Austin, John Noé and
Harold Metcalf, Laser Teaching Center, SUNY at Stony Brook.
Single bubble sonoluminescence (SBSL) is the process of creating light
from the gas in a tiny bubble suspended inside a flask of water by
means of intense ultrasonic sound waves.
Under ideal conditions of dissolved gas and sound field a single
micron-sized bubble will undergo sustained contractions and expansions
in step with the sound pressure fluctuations for many minutes,
emitting very brief (50 picoseconds) flashes of mostly blue and
ultraviolet light every 35 microseconds.
We used the standard SBSL setup in which the intense 25 kHz sound
field is created with two piezo-electric transducers attached on
opposite sides of a standard 100 mL spherical flask and a third
smaller transducer picks up the interaction of the sound waves and the
bubble for display on an oscilloscope.
After some experiments with the degassing procedure, sonoluminescence
was achieved, although the light output seemed to be less than reported
by some others. Our efforts were then directed at improving and fine
tuning the setup to increase the light intensity.
For example, the shape and frequency of the acoustical resonance was
studied as a function of the precise volume of water in the flask
and the degree of degassing. Work is also under way to observe the
sonoluminescence light with a sensitive photomultiplier tube.
This study was supported by NSF Grant No. PHY99-12312.