Strong‐field dressing of vibrational manifolds within ultrafast coherent Raman excitation

Abstract

AbstractThe mechanism of ultrafast, coherent Raman transitions driven at high field strengths is explored in theory and experiment. The study addresses the possibility of maintaining control of a vibrational wavepacket that is guided to a desired final state during the course of a Raman excitation by significantly perturbing the participating molecular states on the time scale of the dynamics under manipulation. Variations in the sequence and amplitude of the pulsed laser fields give direct insight into the nature of the perturbation as well as the population flow within vibrational manifolds of the electronic states involved in the transition. The excitation scheme realized in this work demonstrates control over the dynamics of a molecular system through a non‐adiabatic pathway that utilizes the full manifold of dressed states induced by the laser fields driving the transition rather than isolating the system in a decoupled dressed state common for the adiabatic passage scheme. By preparing highly excited virbrational states in molecular iodine with this scheme, it is shown that a vibrational wavepacket can be steered by controlling the phase with which the character of the field‐free states is introduced into the manifold of dressed states participating in the transition. This scheme seeks to open the possibility of using ultrafast Raman excitation for initiating and observing chemical reactions in the electronic ground state of a molecular system. Copyright © 2007 John Wiley & Sons, Ltd.