Zusammenhang zwischen Schweratominduzierter Fluoreszenzlöschung und Termschema von mehrkernigen aromatischen Kohlenwasserstoffen / Correlation between Heavy-atom induced Fluorescence Quenching and Energy Levels of Polynuclear Aromatic Hydrocarbons

The observation that the fluorescence of certain polynuclear aromatic hydrocarbons (perylene, 1.2 ;5.6-dibenzoperylene, 9.10-diphenylanthracene and rubrene) is quenched by alkyl iodides only slightly is explained on the basis of the energy levels of these hydrocarbons. In these systems an effective radiationless desactivation of the fluorescing state S1 by intersystem crossing into the triplet manifold is prevented by a wide energy gap between S1 and the lowest triplet state, and the absence of excited triplet states below s,.