EXCITONIC AND CHARGE-TRANSFER STATES IN OLIGOMERIC 9,10-ANTHRYLENE CHAINS

The dimer (9,9'-bianthryl), trimer, and tetramer of anthracene, linked in the 9,10-position and equipped with solubility-increasing alkyl su bstituents, were investigated by steady state and time-resolved fluore scence spectroscopy and by transient absorption. In polar solvents, ch arge separation occurs with dipole moments increasing with chain lengt h. The ease of charge separation depends on the energetic competition of the charge transfer (CT) and the lowest excitonic state. It is espe cially favorable for the tetramer in which the CT state was observed e ven in a 77 K frozen alcoholic matrix.