Two-state wave packet for strong field-free molecular orientation

Phys Rev Lett. 2015 Mar 13;114(10):103003. doi: 10.1103/PhysRevLett.114.103003. Epub 2015 Mar 10.

Abstract

We demonstrate strong laser-field-free orientation of absolute-ground-state carbonyl sulfide molecules. The molecules are oriented by the combination of a 485-ps-long nonresonant laser pulse and a weak static electric field. The edges of the laser pulse create a coherent superposition of two rotational states resulting in revivals of strong transient molecular orientation after the laser pulse. The experimentally attained degree of orientation ⟨cosθ⟩≈0.6 corresponds to the theoretical maximum for mixing of the two states. Switching off the dc field would provide the same orientation completely field free.