Progress towards laser cooling of AlCl

Cooling atoms to the ultracold regime has allowed for studies of physics, ranging from many-body physics of quantum degenerate gases, quantum computing, precision measurements and tests of fundamental symmetries. Extending these experiments to polar molecules has the prospect of enhancing the sensitivity of such tests and of enabling novel studies, such as cold controlled chemistry. However, applying traditional laser cooling techniques to molecules is rendered difficult due their additional degrees of freedom which result in a limited photon scattering budget. Here we study aluminum monochloride (AlCl) as a promising candidate for laser cooling and trapping. The cooling transition at 261 nm ($A^{1} \Pi - X^{1} \Sigma^{+}$) has an estimated Franck-Condon factor of 0.9988 which allows for scattering ~800 photons with a single laser before the molecule enters an excited vibrational state. We use a frequency-tripled (SHG + SFG) Titanium-Sapphire laser. We plan to generate AlCl via laser ablation of AlCl$_3$ in a cryogenic helium buffer gas beam source and we will discuss initial spectroscopy on AlCl necessary for future laser cooling and trapping.