O. Rubner et al., Femtosecond time-resolved CARS spectroscopy on binary gas-phase mixtures: A theoretical and experimental study of the benzene/toluene system, J PHYS CH A, 102(48), 1998, pp. 9734-9738
Femtosecond time-resolved CARS measurements on benzene, toluene, and binary
mixtures of these molecules have been performed in the gas phase. Whereas
a two-pulse excitation process prepares benzene in a single vibrational sta
te, a vibrational wave packet is excited in toluene, which gives rise to os
cillatory patterns in the CARS signal. For the mixed system one finds beats
between modes coherently excited in both molecules. The results are analyz
ed using perturbative quantum calculations. It is shown that the rotational
degree of freedom is responsible for the decay of the CARS signal in all c
ases. Furthermore, it is demonstrated that the details of the excitation pr
ocess have to be incorporated in the calculation to obtain the correct ampl
itudes of the oscillating signals.