Energy Balance in the Photochemistry of Benzene

Abstract

Quantum yields of triplet‐state formation in benzene vapor have been determined at several wavelengths by the method of Cundall. From 2520 to 2668 Å, values average about 0.63 if one excludes those at a single wavelength of 2535.5 Å. At this wavelength a higher value is obtained, and its possible significance is briefly discussed. At 2420 Å the triplet‐state yield is small and may be zero. Fluorescent yields have been scanned for ranges of a few Angstrom units from 2400 to 2600 Å. Above 2520 Å there is no significant change with wavelength. The trends in these results are briefly discussed, and it is pointed out that a detailed discussion of the theory of the photochemistry of benzene has little value because data now available are not sufficient to test any theory.