The effect of ultrasound on photochemical reactions.

Sonochemistry and photochemistry are based on very different physical phenomena, which a priori seems to exclude any possibility to observe more than a simple superposition of their respective effects. Literature data are examined, first the few studies devoted to sonochemical and photochemical reactions in cases where a direct comparison is possible. The second part is devoted to an analysis of experiments in which both irradiations are effected simultaneously. Cases exist from which it can be concluded, at least provisionally, that sonication is able to quench long-lived excited states, because of the intense streaming which enhances strongly the probability of collisional deactivations.