EXCITON-TO-BIEXCITON TRANSITION IN QUASI-ONE-DIMENSIONAL ORGANICS

In the previous paper we demonstrated novel multiexcitons in a neutral mixed-stack charge-transfer solid. The lowest multiexciton, the biexc iton, has recently been of interest also in the context of quasi-one-d imensional organic materials that are different from the mixed-stack s olids. The nature and strength of the optical transition from the exci ton to the two-exciton states is of importance in understanding photoi nduced absorption as well as two-photon absorption. We show that withi n the diverse theoretical models that describe these different classes of materials, the excited state absorption from the optical exciton t o the two-exciton states changes in a fundamental way upon the formati on of the biexciton. The identical nature of the exciton absorption wi thin these models is a consequence of one dimensionality. (C) 1996 Ame rican Institute of Physics.