Observation of quantum coherence for recurrence motion of exciton in anthracene dimers in solution.

The quantum beat signal associated with recurrence motion of exciton was observed for two types of anthracene dimers connected through a phenyl ring, on femtosecond fluorescence anisotropy decay. The time periods of oscillation were 0.3-0.9 ps, which correspond to exciton interactions of 30-50 cm-1, and the damping time constants (dephasing time) were 0.7-1.0 ps. The results show that the coherent aspect in photochemical processes is observable even in solution at room temperature, if one employs dimers of rigid structures.