The Natural Phosphorescence Lifetime of Biacetyl and Benzil in Fluid Solution

The quantum yields of phosphorescence and fluorescence and the phosphorescence lifetime have been determined for biacetyl in benzene, p‐xylene, n‐heptane, and water, and for benzil in n‐heptane at 22d̀C. The following values for the fluorescence quantum yield and natural phosphorescence lifetime were obtained: For biacetyl in benzene, 2.7 times 10 ‐3 and 7.8 msec, in p‐xylene, 2.5 times 10 ‐3 and 10.8 msec, in n‐heptane, 2.9 times 10 ‐3 and 10.8 msec, in water, 1.1 times 10 ‐3 and 10.0 msec, and for benzil in n‐heptane, 1.1 times 10 ‐3 and 10.4 msec.