Abstract
An hydrodynamic model for single bubble sonoluminescence (SBSL) taking into account dissociation in diatomic gases and ionization in monoatomic ones is presented. Bubble inertial effects are neglected and a uniform interior approximation is employed. The Gilmore approximation for the bubble radius equation is used and heat conduction at the bubble boundary is included in ad hoc way. Dissociation and ionization are included in a self-consistent way in the gas energy equation by relaxing the commonly used thermodynamic equilibrium hypothesis and introducing proper rate equations. The cases of oxygen and nitrogen bubbles are considered, showing that an appreciable amount of dissociated moleculae should be produced when O2 fills the cavity while dissociation should be negligible in the case of N2. All inert gases are also considered and it is shown that ionization levels should be very low in the case of He and Ne, while an appreciable increasing amount of ionized atoms should be produced in Ar, Kr, Xe and Rn bubbles. The obtained maximum gas temperatures for monoatomic gases are all close to 20000 K, thanks to a special combination of heat conduction and ionization effects, corroborating some theoretical previsions on SBSL light emission mechanism based on free electron transitions.
