Adiabatic field-free alignment of asymmetric top molecules with an optical centrifuge

TL;DR

This study demonstrates adiabatic, field-free alignment of asymmetric top molecules using an optical centrifuge, revealing persistent planar alignment and periodic 3D alignment, with potential for advanced molecular control.

Contribution

It introduces a method for adiabatic, field-free alignment of asymmetric top molecules via an optical centrifuge, including the observation of periodic 3D alignment.

Findings

Persistent planar molecular alignment after centrifuge release

Periodic 3D alignment observed in asymmetric top molecules

Molecular bending up to 10 degrees due to centrifugal forces

Abstract

We use an optical centrifuge to align asymmetric top $\mathrm{SO_2}$ molecules by adiabatically spinning their most polarizable O-O axis. The effective centrifugal potential in the rotating frame confines sulfur atoms to the plane of the laser-induced rotation, leading to the planar molecular alignment which persists after the molecules are released from the centrifuge. Periodic appearance of the full three-dimensional alignment, typically observed only with linear and symmetric top molecules, is also detected. Together with strong in-plane centrifugal forces, which bend the molecules by up to 10 degrees, permanent field-free alignment offers new ways of controlling molecules with laser light.