Activation of Ru(bpy) multibubble sonochemiluminescence in alkaline aqueous solutions by a hydrated electron.

The sonochemiluminescence in 10 M aqueous solutions of Ru(bpy)Cl was studied in the presence of NaOH and KOH (up to 0.4 M). The observed increase in the steady-state emission intensity from Ru(bpy) as compared with the intensity in neutral solutions was attributed to conversion of H resulting from water sonolysis to e. As a result, there is a multiple (>10) change in the concentrations of the sonochemical intermediates Ru(bpy) and Ru(bpy). The reduction of the Ru(bpy) ion with H, which is of low efficiency for the formation of the excited *Ru(bpy) ion, is replaced by reduction with hydrated electron, in which *Ru(bpy) is generated in a high yield. The participation of e provides a fivefold increase in the sonochemiluminescence intensity in a key disproportionation reaction: Ru(bpy) + Ru(bpy) → Ru(bpy) + *Ru(bpy). It was shown that chemiluminescence from reduction of intermediate Ru(bpy) with the OH ion does not make a pronounced contribution to the sonochemiluminescence intensity.