Establishing a nearly closed cycling transition in a polyatomic molecule
Louis Baum, Nathaniel B. Vilas, Christian Hallas, Benjamin L. Augenbraun, Shivam Raval, Debayan Mitra, John M. Doyle
Abstract
We study optical cycling in the polar free radical calcium monohydroxide (CaOH) and establish an experimental path towards scattering $\ensuremath{\sim}{10}^{4}$ photons. We report rovibronic branching ratio measurements with precision at the $\ensuremath{\sim}{10}^{\ensuremath{-}4}$ level and observe weak symmetry-forbidden decays to bending modes with nonzero vibrational angular momentum. Calculations are in excellent agreement with these measurements and predict additional decay pathways. Additionally, we perform high-resolution spectroscopy of the $\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{X}{\phantom{\rule{1.0pt}{0ex}}}^{2}{\mathrm{\ensuremath{\Sigma}}}^{+}({12}^{0}0)$ and $\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{X}{\phantom{\rule{1.0pt}{0ex}}}^{2}{\mathrm{\ensuremath{\Sigma}}}^{+}({12}^{2}0)$ hybrid vibrational states of CaOH. These advances establish a path towards radiative slowing, three-dimensional magneto-optical trapping, and sub-Doppler cooling of CaOH.