Quantum beating of vibrational factor group components in molecular solidsa)

Abstract

We report the first observation of coherent Raman induced quantum beats from exciton states in molecular crystals. The paper describes the relevant crystal optics and phasematching conditions needed to ensure coherent excitation of more than one Raman transition in an anisotropic solid. The study of the 991 cm⁻¹ mode of C₆H₆ at 1.6 K has allowed the identification of two nearby (0.6 cm⁻¹) factor group components and their lifetimes. The larger damping of the weaker A_g→B_2g transition suggests that intraband scattering is operative.