Laser Induced Gas Vortices

TL;DR

This paper demonstrates that femtosecond laser pulses can induce unidirectional molecular rotation, which through angular momentum conservation generates macroscopic vortex flows in the gas, resembling Taylor vortices.

Contribution

It introduces a novel method of creating macroscopic gas vortices via laser-induced molecular rotation and explores the resulting flow dynamics.

Findings

Laser pulses induce unidirectional molecular rotation.

Rotational states lead to macroscopic vortex flows.

Repeated excitation stirs the gas continuously.

Abstract

Properly polarized and correctly timed femtosecond laser pulses have been demonstrated to create rotational states with a preferred sense of rotation. We show that due to conservation of angular momentum, collisional relaxation of these unidirectionally rotating molecules leads to the generation of macroscopic vortex flows in the gas. The emerging velocity field converges to a self-similar Taylor vortex, and repeated laser excitations cause a continuous stirring of the gas.