Insights into Hypermetallic Molecules En Route to Multiple Optical Cycling Centers: Thermodynamic and Spectroscopic Trends in Mg and Ca Bearing Acetylides.

Hypermetallic molecules have been proposed as novel candidates for laser cooling and precision physics measurements, but species such as CaCCMg have yet to be synthesized and detected, despite recent successes in characterizing other related species of fundamental and astrochemical interest. Here, we examine the thermodynamics of the relevant alkaline earth metal chemistry with an acetylene precursor via ab initio electronic structure calculations. Experimental measurements of optical emission from a discharge-assisted laser ablation expansion source highlight the potential importance of electronically excited atoms in producing the desired species.