Orienting Asymmetric Molecules by Laser Fields with Skewed Polarization

TL;DR

This paper investigates how pairs of strong, time-delayed laser pulses with crossed linear polarizations can induce unidirectional rotation and transient orientation in asymmetric chiral molecules, with potential applications in chiral analysis.

Contribution

It reveals the classical mechanism behind laser-induced molecular orientation using skewed polarization and explores applications in chiral molecule discrimination.

Findings

Laser pulses induce unidirectional rotation of molecules.

Opposite enantiomers experience opposite orienting torques.

The mechanism is classical and can be used for chiral analysis.

Abstract

We study interaction of generic asymmetric molecules with a pair of strong time-delayed short laser pulses with crossed linear polarizations. We show that such an excitation not only provides unidirectional rotation of the most polarizable molecular axis, but also induces a directed torque along this axis, which results in the transient orientation of the molecules. The asymmetric molecules are chiral in nature and different molecular enantiomers experience the orienting action in opposite directions causing out-of-phase oscillation of their dipole moments. The resulting microwave radiation was recently suggested to be used for analysis/discrimination of chiral molecular mixtures. We reveal the mechanism behind this laser induced orientation effect, show that it is classical in nature, and envision further applications of light with skewed polarization.