Photooxidation of Leuco Dyes. III. Sensitized Photooxidation of Leuco FluoresceinQuantum yields of the sensitized photooxidation of leuco fluorescein are reported. Fluorescein and benzophenone were found to be efficient sensitizers of photooxidation of leuco fluorescein. There is a characteristic dependence of quantum yields on concentration of leuco fluorescein and oxygen in the solution. The results are discussed on the basis of reaction scheme proposed for the sensitized formation of fluorescein.