High resolution study of 1388 cm(-1) CO2 vibration by time-domain CARS: spectral exchange and Dicke effect

The dephasing kinetics of the higher frequency component of the Fermi-resor tance dyad nu(1)/2 nu(2) (1388 cm(-1)) of CO2 was studied by means of time- domain CARS in the density range where spectral exchange and Dicke effect p lay a noticeable role. The spectral exchange manifests itself in the gradua l shift to longer delay times of minima and maxima of the beats between dif ferent Q-branch components with increasing densities and in the simultaneou s beats smoothing. As a result of both the effects, the pulse response was practically exponential at CO2 densities greater than or equal to 0.4 Amaga t. (C) 2000 Published by Elsevier Science B.V. All rights reserved.