Spectroscopy for Laser Cooling and Trapping 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 to 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. We use a frequency-tripled (SHG + SFG) Titanium-Sapphire laser and generate AlCl via laser ablation of AlCl₃ in a cryogenic helium buffer gas beam source. We discuss our spectroscopy measurements of the laser cooling line, our experimental estimates for the Franck-Condon factor of the ν = 0 → ν’ = 0 transition and ab-intio calculations of the potential energy surfaces of the X¹Σ⁺ and A¹Π states.