Enhancement of resonant bleaching of J-aggregates upon lengthening of an exciting radiation

Abstract

Thin films of J-aggregates of a new amphiphilic thiacarbocyanine dye of the benthiazole series are prepared and the nonlinear optical response of molecular J-aggregates is studied for femto-and nanosecond exciting radiation pulses. It is found that the nonlinear optical response of J-aggregates exhibits substantial enhancement upon an increase in the pulse duration, which cannot be described by the saturation effect in the model of a two-level system. This effect is considered using a three-level model taking into account the formation of self-trapped exciton states in molecular J-aggregates.