Pump-probe spectrum of interacting one-dimensional excitons: biexcitons and J-aggregates

The third-order differential pump-probe absorption spectrum for interacting one-dimensional Frenkel excitons is calculated analytically. In the J-aggregate configuration (J < 0) a red-shifted biexciton peak appears when A < 2J, where J is the near-neighbor transfer integral and A is the exciton-exciton interaction strength.