High resolution study of 1388 cm−1 CO2 vibration by time-domain CARS: spectral exchange and Dicke effect Original Research Article

The dephasing kinetics of the higher frequency component of the Fermi-resonance dyad ν1/2ν2 (1388 cm−1) of CO2 was studied by means of time-domain CARS in the density range where spectral exchange and Dicke effect play a noticeable role. The spectral exchange manifests itself in the gradual shift to longer delay times of minima and maxima of the beats between different Q-branch components with increasing densities and in the simultaneous beats smoothing. As a result of both the effects, the pulse response was practically exponential at CO2 densities ⩾ 0.4 Amagat.