International Workshop on Atomic Interactions in Laser Fields - Abstracts
Instytut Fizyki, Uniwersytet M. Kopernika, Grudziadzka 5, 87-100 Torun, Poland
The phenomenon of sonoluminescence has been known for more than 60 years, but it was not until a decade ago that stable light emission from a single gas bubble in an acoustic field was obtained by Gaitan et al. . The authors found that a single gas bubble could be levitated in a standing wave acoustic field and made to emit light pulses synchronized to the acoustic cycle. Spectral and temporal properties of the single bubble sonoluminescence (SBSL) have been investigated [2-4] and it was found that broadband (~200-700 nm) SBSL light is emitted in the form of ultrashort pulses with duration ≤ 200 ps (see  for a review of experimental data and theories on SBSL). The study of the SBSL light emission mechanism spans various subjects of physics and chemistry, including optics, acoustics, thermodynamics, fluid dynamics, spectroscopy and quantum electrodynamics.
A broad range of possible theoretical explanations of the light emission mechanism includes the dynamic Casimir effect, proton-tunneling radiation, tribo-, fracto- and flexoluminescence, thermal bremsstrahlung and electron-ion recombination , collective spontaneous emission, collision-induced emission and electron-atom bremsstrahlung. Although the light emission mechanism still remains a subject of controversy, possible applications seem to be very promising. For example, a novel optical imaging technique based on this phenomenon ("sonoluminescent tomography") has been proposed recently by Wang and Shen , who applied multiple-bubble sonoluminescence in their studies of strongly scattering solutions.
Our investigations at the Institute of Physics in Torun are aimed both at elucidating the light generation mechanism of the SBSL and at optimizing the experimental conditions in order to develop an effficient, inexpensive picosecond light source for studies of the ultrafast fluorescence kinetics.
In the present lecture, an overview of existing experimental data and known theoretical models of the SBSL phenomenon will be given. The author will also present the results of his own experiments and briefly sketch the planned investigations.