Exciton Percolation: Isotopic-MixedB2u1Naphthalene

We propose a percolation model for an exciton insulator-to-conductor transition. Experimentally, we investigate (at 2°K) the first singlet exciton in a binary organic alloy of naphthalene-perdeuteronaphthalene. A third component, ${10}^{-3\mathrm{}}$-mole-fraction betamethyl-naphthalene, serves as exciton-flow monitor, and the integrated relative fluorescence is derived. The ${}_{}{}^1{}_{}{}^{}B_{2\mathrm{u}}^{}{}_{}{}^{}$ Frenkel-exciton data are bound by the theoretical site-percolation curves for square and simple-cubic lattices.