Non-adiabatic effects in laser orientation ad alignment of molecules (Prof. González Férez)

In these experiments, pendular states were created by means of linearly polarized strong laser pulses combined with tilted weak electrotrastic fields. Our calculations, which take account the temporal profile of the experimental laser pulses, demonstrate the relevance of non-adiabatic processes in the field-dressed molecular dynamics. For perpendicular fields, one obtains pure alignment, and our simulations reproduce the strongly driven quantum pendulum in the angular motion of the OCS molecule in a picosecond laser pulse. For tilted fields, we show that a fully adiabatic description of the process does not reproduce the experimentally observed orientation and that under currents laser pulses the weak dc field orientation is, in general, not adiabatic, so that a time-dependent description of the orientation process becomes mandatory. We explore the importance of non-adiabatic effects and provide a revised condition for achieving adiabatic mixed-field orientation.