ANISOTROPIC S-1-T-1 INTERSYSTEM CROSSING OF 1-CHLOROMETHYLNAPHTHALENE

Relative populating rates and zero-field splitting parameters of the l owest triplet state of naphthalene derivatives were measured by time-r esolved ESR. In most of the naphthalene derivatives, in-plane triplet sublevels were more populated than out-of-plane sublevels by S-1-T-1 i ntersystem crossing (ISC), whereas the highest in-plane sublevel was l ess populated than the other sublevels in 1-chloromethylnaphthalene (1 CMN). This exceptional anisotropy in the ISC of 1CMN was interpreted b y the internal heavy atom effect of the chlorine atom.