Bubbles filled with gas can emit light when collapsing violently in a surrounded liquid upon strong excitation. A great interest in collapsing bubbles in the last two decades is associated with observation of single bubble sonoluminescence (SBSL) which is a light emission phenomenon of stable oscillating bubble in liquid irradiated by a periodic ultrasound wave field. Another method of single bubble investigation is provided by cavitation. Single cavitation bubble luminescence (SCBL) in contrast to SBSL does not need a sound field for the emission of light, it just follows a Rayleigh collapse.

Because of enormous compression rates, high temperatures occur inside those bubble which can reach up to 50000 K, leading to visible light emission at collapse time. The remarkable aspectof this phenomenon is the high concentration of energy. But there are limits that bound the possibilities to go beyond this point imposed by different kinds of instabilities and processes.

In this work we show the effects of two factors involved in the concentration of energy. The presence of vapor near the time when a SBSL bubble collapses and the Rayleigh-Taylor (RTI) instability associated with bubble breakoff in SBSL and SCSL.

To study vapor effect, we concentrated on the determination of the accommodation coefficient that made experimental and
numerical results compatible for a stable Xenon sonoluminescent bubble in a 85 eight sulfuric acid aqueous solution using non-linear least square fitting to estimate three parameters. While to study RT instability we approach to the problem performing a classical linear analysis perturbation of the bubble shape.