Cooperative disordering processes in J-aggregates - difference absorption spectra caused by dynamical disorder

The strong excitation-induced changes in J-aggregates, when taking into acc ount the disorder, produced by the exciton-exciton annihilation due to the excess energy redistribution, are discussed. Theoretical analysis of the pu mp intensity-dependent differential absorption spectra on the basis of the presented off-diagonal disordering model is made, concluding that the inten sity-dependent blue shift of difference absorption spectra may result from the disorder induced by the degradation of the excess energy after the exci ton-exciton annihilation event. (C) 1999 Elsevier Science B.V. All rights r eserved.