Bremsstrahlung of nitrogen and noble gases in single-bubble sonoluminescence

A hydrodynamic model, discussing neutral gases as well as plasmas, is appli ed to simulate single-bubble sonoluminescence. in this model, thermal condu ction and various inelastic impact processes such as dissociation, ionizati on, and recombination are considered. Bremsstrahlung is assumed as the mech anism of the picosecond light pulse in sonoluminescence. Diatomic nitrogen and noble gas bubbles are studied. The results show that the sonoluminescin g bubbles are completely optically thin for bremsstrahlung. The calculated spectra agree with previous observations, and can explain the observed diff erences in spectra of different gases.