Sonoluminescence of aqueous solutions of sulfuric acid and sulfur dioxide

Sonoluminescence (SL) of aqueous solutions of sulfuric acid and sulfur dioxide enhances with an increase in their concentration and reaches a maximum at 16 and 0.05 mol L-1, respectively. The further increase in the concentration of these substances decreases the SL intensity. The SL spectra of the solutions have a broad maximum at 450 nm. Excited SO2 molecules formed in sulfuric acid due to sonolysis are luminescence emitters. The proposed mechanism of bright SL in these systems is based on the energy transfer from the electron-excited sonolysis products to the SO2 molecules in cavitation bubbles.