Intersystem crossing quantum yield of quinoxaline; Evidence for high yield of internal conversion of the first excited singlet state to the ground state

The intersystem crossing quantum yield of quinoxaline has been directly determined to be 0.18 +/- 0.04 at the temperature of boiling nitrogen. The absence of fluorescence indicates a value of 0.82 +/- 0.04 for the quantum yield for internal conversion from the first excited singlet.