Matrix isolation of Mg2 and Mgn molecules in neon,argon, and nitrogen hosts

The Mg₂ and Mg_n molecules have been formed and studied in neon, argon, and nitrogen matrices at approximately 4° and 12 K. Bands observed between 2000 and 3500 Å have been investigated as a function of gradual changes in trapping conditions and assigned to various stages of magnesium atom polymerization. The A¹Σ_u⁺ ← X¹Σ_g⁺ system of Mg₂ relative to the gas exhibits a pronounced red shift which increases with the polarizability of the matrix host. A band at 2653 Å in argon was observed which can be tentatively assigned to another Mg₂ system.