  Aluminum monochloride (AlCl) has been proposed as a promising candidate for
laser cooling to ultracold temperatures, and recent spectroscopy results
support this prediction. It is challenging to produce large numbers of AlCl
molecules because it is a highly reactive open-shell molecule and must be
generated in situ. Here we show that pulsed-laser ablation of stable, non-toxic
mixtures of Al with an alkali or alkaline earth chlorides, denoted XCln, can
provide a robust and reliable source of cold AlCl molecules. Both the chemical
identity of XCln and the Al:XCln molar ratio are varied, and the yield of AlCl
is monitored using absorption spectroscopy in a cryogenic gas. For KCl, the
production of Al and K atoms was also monitored. We model the AlCl production
in the limits of nonequilibrium recombination dominated by first-encounter
events. The non-equilibrium model is in agreement with the data and also
reproduces the observed trend with different XCln precursors. We find that AlCl
production is limited by the solid-state densities of Al and Cl atoms and the
recondensation of Al atoms in the ablation plume. We suggest future directions
for optimizing the production of cold AlCl molecules using laser ablation.
