Excitonendiffusion in Naphthalin-Aufdampfschichten

Abstract

Films of pure naphthalene and such doped with about 10-2 iodobenzene are evaporated. The diffusion length of singlet excitons in evaporated naphthalene is found to be 250 Å at 77 °K and 500 A at 170 °K. Besides the well known fluorescence of naphthalene the films show increasing emission from lattice defects with decreasing temperature. Therefore it is impossible to deduce the mechanism of exciton diffusion from the temperature dependence of the diffusion length. Energy migrates from naphthalene to anthracene guest molecules in an easier way than in single crystals. Surface quenching of singlet excitons in evaporated films is demonstrated.