Dynamics of vibrational wavepackets excited by a phase-modulated femtosecond light pulse in I-2

The "pumping-probing" technique is employed to study the effect of phase mo dulation of the exciting pulse on time evolution of vibrational wavepackets in state B of an I-2 molecule. The controlled phase modulation of an excit ing pulse was achieved by passing the pulse through a medium with a known d ispersion. The dynamics of wave packets formed is shown to appreciably depe nd on the value and sign of phase modulation of the exciting pulse. This re sult demonstrates the potential feasibility of application of phase modulat ion to govern intramolecular dynamics and the necessity of controlling the pulse structure to adequately interpret signals observed in "pumping-probin g" experiment.