Effect of ultrasound frequency on sonochemical luminescence under well-determined sound pressure

By determining sound pressure using the Ramann-Nath parameter and confirmin g sound form based on schlieren images, we investigated the effects of ultr asound frequency on the sonochemical luminescence of a luminol solution. Se parating the effect into the luminescence threshold of sound energy and the rate of luminescence increase with respect to the sound energy, we found t hat the lower the frequency is the lower the threshold and the higher the r ate of increase, and that only the standing-wave induces luminescence under the conditions where the running-wave does not induce luminescence at all.