Molecular Orientation-Induced Second Harmonic Generation: deciphering different contributions apart

TL;DR

This paper introduces 'MOISH', an all-optical method for monitoring gas-phase molecular orientation dynamics through second harmonic generation, revealing electronic and nuclear contributions and enabling controlled rotational studies.

Contribution

The paper presents a novel all-optical technique, 'MOISH', that directly probes molecular orientation dynamics and distinguishes different dynamical contributions in gas media.

Findings

'MOISH' effectively detects orientation dynamics in gas molecules.

The technique separates electronic and nuclear contributions to the nonlinear signal.

It enables exploration of controlled rotational dynamics with terahertz and optical fields.

Abstract

We demonstrate and explore an all-optical technique for direct monitoring the orientation dynamics of gas phase molecular ensembles. The technique termed 'MOISH' utilizes the transiently lifted inversion symmetry of polar gas media and provides a sensitive and spatially localized probing of second harmonic generation signal that is directly correlated with the orientation of the gas. Our experimental results reveal selective electronic and nuclear dynamical contributions to the overall nonlinear optical signal and decipher them apart using the "reporter gas" approach. 'MOISH' provides new, crucial means for exploring controlled rotational dynamics via concerted terahertz and optical field excitation.