Photophysics and photochemistry ofo-xylene solutions II. Radiationless processes

Abstract Data are presented for triplet yield measurements on o -xylene solutions as a function of temperature and concentration. Intersystem crossing from the excited singlet monomer is independent of temperature ( k ISCM = 7.2 × 10 6 s −1 ). Internal conversion has temperature independent ( k 0 ICM = 3.9 × 10 6 s −1 ) and temperature dependent components. For the later E ICM is 0.207 eV and A 2.2 × 10 10 s −1 ). The results are interpreted on the basis of a recent model for radiationless decay. The intrinsic yields for intersystem crossing and internal conversion from the o -xylene excimer are also estimated.