Making the best of mixed-field orientation of polar molecules: a recipe for achieving adiabatic dynamics in an electrostatic field combined with laser pulses.

We have experimentally and theoretically investigated the mixed-field orientation of rotational-state-selected OCS molecules and achieved strong degrees of alignment and orientation. The applied moderately intense nanosecond laser pulses are long enough to adiabatically align molecules. However, in combination with a weak dc electric field, the same laser pulses result in nonadiabatic dynamics of the mixed-field orientation. These observations are fully explained by calculations employing both adiabatic and nonadiabatic (time-dependent) models.