Control of molecular rotation with a chiral train of ultrashort pulses

TL;DR

This paper introduces a novel method using chiral trains of ultrashort laser pulses with rotating polarization to control molecular rotation, enabling selective and directional excitation with conventional pulse shaping techniques.

Contribution

The work presents a new control parameter—chirality of pulse trains—for selective and directional molecular rotational excitation, utilizing pulse trains with many pulses separated by femtoseconds.

Findings

Chiral pulse trains enable control of molecular rotation.

The method achieves selectivity and directionality in rotational excitation.

Conventional pulse shapers can be used for implementation.

Abstract

Trains of ultrashort laser pulses separated by the time of rotational revival (typically, tens of picoseconds) have been exploited for creating ensembles of aligned molecules. In this work we introduce a chiral pulse train - a sequence of linearly polarized pulses with the polarization direction rotating from pulse to pulse by a controllable angle. The chirality of such a train, expressed through the period and direction of its polarization rotation, is used as a new control parameter for achieving selectivity and directionality of laser-induced rotational excitation. The method employs chiral trains with a large number of pulses separated on the time scale much shorter than the rotational revival (a few hundred femtosecond), enabling the use of conventional pulse shapers.