Cold CH radicals for laser cooling and trapping

Abstract

Ultracold CH radicals promise a fruitful testbed for probing quantum-state controllable organic chemistry. In this work, we calculate CH vibrational branching ratios (VBRs) and rotational branching ratios (RBRs) with ground state mixing. We subsequently use these values to inform optical cycling proposals and consider two possible radiative cooling schemes using the $X^2\Pi \leftarrow A^2\Delta$ and $X^2\Pi \leftarrow B^2{\Sigma }^{-}$ transitions. As a first step towards laser cooled CH, we characterize the effective buffer gas cooling of this species and produce $\sim 5\times 10^{10}$ CH molecules per pulse with a rotational temperature of 2(1) K and a translational temperature of 7(2) K. We also determine the CH-helium collisional cross section to be $2.4(8)\times 10^{-14}$ cm${}^2$. This value is crucial to correctly account for collisional broadening and accurately extract the in-cell CH density. These cold CH molecules mark an ideal starting point for future laser cooling and trapping experiments and tests of cold organic chemistry.

17 pages, 5 figures

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Cited by in corpus (1)

• Optimizing Pulsed-Laser Ablation Production of AlCl Molecules for Laser Cooling