Dephasing of Excitonic Transition of J-Aggregates Measured by Time-resolved Resonance CARS

Abstract

J-aggregates are the subject of great interest due to high values of optical susceptibilities of intensive excitonic resonance, originated from delocalization of electronic excitation in molecular aggregate. In [1,2] resonant enhancement of third-order susceptibiltity of J-aggregates of pseudoisocyanine (PIC) solutions was observed. The dephasing time of excitonic transition of PIC J-aggregate solutions was determined in [3] as 16 ps by low-temperature photon echo, and T2=0.17 ps at room temperature by measuring the dispersion of nonlinear susceptibility in the process of four-wave mixing [2].