Stability of a sonoluminescing nitrogen bubble in chilled water

Bubbles are levitated in a resonator driven by an ultrasound wave. Their highly nonlinear oscillations feature a strong collapse, where fluidlike densities and temperatures of several thousand degrees Kelvin are reached, resulting in the emission of ultrashort light pulses. Previous experiments and theories explained the observed stable bubble dynamic and emission on long time scales with the requirement of a noble gas. Recent experiments reveal stable sonoluminescent emission of nitrogen bubbles in chilled water without the presence of a noble gas. Numerical calculations show that a diffusive and dissociative equilibrium can be reached when the temperature within a nitrogen bubble is limited due to the presence of water vapor. Calculated stability lines agree with published experimental results. The results show that noble-gas-free stable single bubble sonoluminescence of nitrogen bubbles is possible.