Figure 6.

Exciton energy diagram illustrating the dynamics of pump-dump-probe response. Potential energy E as a function of an effective nuclear coordinate Q is shown for the ground (g), and three lowest exciton states (k = 0, −1, 1) of the circular aggregate. Blue arrows indicate ultrafast exciton equilibration from higher exciton states (not seen in this experiment) and the red arrow indicates the equilibration between k = 0 and k = 1. Magenta arrows indicate the vibrational wavepacket motion, in phase, imposed on this equilibration, from k =1 to k = 0. (This picture is taken from Novoderezhkin et al. (61).)