Sonoluminescence - this phenomenon by which air bubbles in a liquid taken emit a flash of light under the effect of acoustic waves - has been described by scientists for a long time. But its mechanisms remain unknown.
David Flannigan and Kenneth Suslick of the University of Illinois at Urbana Champaign, took a further step in understanding the process managing to create a single argon bubble in a sulfuric acid solution. Under the action of sound waves of frequencies above 18000 cycles per second, the bubble is first dilated before reaching its limits and then rapidly collapse. It was during this last stage we observe light emission. Through their work, the two researchers were able to obtain a spectrum 3000 times brighter than previous experiments. This allowed them to make a more detailed analysis of the event. According to their action, the local temperature reached 15000 Kelvin, several times the surface temperature of the sun. But the more remarkable is the argon atoms and oxygen detecting high energy ionized during the experiment.
A result that traditional chemical and thermal reactions do not explain and that the authors of the research therefore attribute to the collision of atoms with electrons and ions of very high energy hot plasma as formed in the core of the bubble. If these data are confirmed, they would constitute the first direct detection of plasma associated with the sonoluminescence.
NYT 15 / 03 / 04 (Tiny bubbles implode with
the heat of a star) http://www.nytimes.com/2005/03/15/science/15soni.html