Knowledge Bank

The spin sublevel origins of both radiative and non-radiative decays have been $determined1$ for benzene from the temperature dependence of precisely measured phosphorescence lifetimes in several glasses and crystals, in which electron spin-lattice relaxation (SLR) is fast. A more pronounced temperature effect, found in stable cyclohexane, is due to slower SLR. A simplified model and transient time and intensity measurements yield SLR rates whose temperature dependence and behaviors in magnetic fields and under selective microwave irradiation will be seen to support the assumptions of the model.