Die Beeinflussung der optischen Absorption von Molekülen durch ein elektrisches Feld

The effect of an external electric field on the optical absorption of molecules in solution allows certain components of the polarizability tensors in the ground state and in excited electronic states to be determined. Electrooptical absorption measurements were performed on some aromatic hydrocarbons (anthracene, tetracene, perylene, bianthryl) and some tetraphenylpolyenes at different temperatures and in different solvents. For the aromatic hydrocarbons, the polarizabilities in the first excited singlet state were found to be 20 to 70 p.c. greater than those in the ground state. The increases are either mainly parallel or mainly perpendicular to the direction of the transition moment of the absorption bands. For the tetraphenylpolyenes, the measurements yielded much greater increases of up to 400 p.c. almost totally in the directions of the transition moments, which are approximately in the directions of the chains. Fluctuation effects of the local electric field were observed, they may be interpreted using the extended model 9.