Radiation Pressure Force from Optical Cycling on a Polyatomic Molecule

TL;DR

This paper demonstrates optical cycling and radiative force deflection on SrOH molecules, paving the way for laser cooling of polyatomic molecules by scattering around 100 photons per molecule.

Contribution

It introduces a method for photon cycling on a polyatomic molecule, SrOH, using a specific vibronic transition and a single repumping laser, enabling radiative force application.

Findings

Achieved deflection of SrOH beam by 0.2 degrees.

Scattered approximately 100 photons per molecule.

Demonstrated potential for laser cooling of complex molecules.

Abstract

We demonstrate multiple photon cycling and radiative force deflection on the triatomic free radical strontium monohydroxide (SrOH). Optical cycling is achieved on SrOH in a cryogenic buffer-gas beam by employing the rotationally closed $P\left(N''=1\right)$ branch of the vibronic transition $\tilde{X}^{2}\Sigma^{+}\left(000\right)\leftrightarrow\tilde{A}^{2}\Pi_{1/2}\left(000\right)$. A single repumping laser excites the Sr-O stretching vibrational mode, and photon cycling of the molecule deflects the SrOH beam by an angle of $0.2^{\circ}$ via scattering of $\sim100$ photons per molecule. This approach can be used for direct laser cooling of SrOH and more complex, isoelectronic species.