INCOHERENT EXCITON PERCOLATION: ISOTOPIC MIXED $^{1}B_{2{u}}$ NAPHTHALENE

Abstract

When the effective aggregate size becomes much larger than the diffusion length of the exciton (within its lifetime), the energy transfer process becomes mobility limited. Experimentally, one drastically reduces the concentration of the exciton-monitoring supertraps (betamethylnaphthalene and perdeuterobetamethylnaphthalene) compared to the coherent percolation case (Monberg and Kopelman, previous abstract), while investigating the $2^{\circ} K$ fluorescence spectra of $C_{10}H_{8}$/$C_{10}D_{8}$ crystals as a function of the $C_{10}H_{8}$ concentration. The results are compared to classical effective medium theory and electron mobility percolation. The exciton incoherence will be discussed in terms of diffusion and trapping efficiency.