Role of the triplet state in the benzene-sensitized decomposition of chloroform

Abstract

A study has been made of the effect of increasing chloroform pressure on benzene and biacetyl emission under various conditions. No quenching of benzene fluorescence by chloroform is observed when excitation is by 2570 Å radiation, whether or not biacetyl is present. On the other hand, quenching of the sensitized biacetyl phosphorescence is pronounced. However, it is demonstrated that chloroform does not quench biacetyl phosphorescence when excitation occurs at 3660 Å, from which it can be concluded that chloroform preferentially accepts energy from the benzene triplet rather than the excited singlet. Therefore it is probably the triplet which is responsible for the benzene-photosensitized decomposition of chloroform previously reported.