Multipulse polarisation selective spectroscopy of rotational and vibrational responses of molecules in a liquid

The amplitude control of time-resolved optical responses in a liquid is theoretically analysed under nonresonant irradiation of the system by a train of femtosecond pulses with parallel and orthogonal polarisations. The control parameters, specifying the excitation scenarios, are the duration of pulses, their relative intensities, polarisation, and the delays between the pulses. It is shown that the choice of specific excitation scenarios transfers the system into a state in which only one response is detected from a set of responses of coherent intramolecular Raman active vibrational modes, coherent molecular librations and orientational rotations.