Coherent rovibrational revivals in a thermal molecular ensemble

We report an experimental and theoretical study of the evolution of vibrational coherence in a thermal ensemble of nitrogen molecules. Rotational dephasing and rephasing of the vibrational coherence is detected by coherent anti-Stokes Raman scattering. The existence of rovibrational coupling and the discrete energy spectrum of the rotational bath lead to a whole new class of full and fractional rovibrational revivals. Following the rich rovibrational dynamics on a nanosecond time scale with subpicosecond time resolution enables us to determine the second-order rovibrational constant gamma(e) and assess new possibilities of controlling decoherence.