Polarization CARS of pyrene in the SI state has been observed in solution at room temperature under the resonance condition with the Sn -SI transient absorptions. The polarization behaviors of totally symmetric a g and nontotally symmetric big modes have been interpreted on the basis of an irreducible tensor formulation of the polarization CARS susceptibility which is applicable rigorously in resonance conditions, and anomalous depolarization ratio for the big mode corresponding to the case of PI> 3/4 in spontaneous Raman scattering has been deduced.

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