Experimental and theoretical study of the Sn – O bond formation between atomic tin and molecular oxygen

The merging of the electronic structure calculations and crossed beam experiments expose the reaction dynamics in the tin (Sn, ³P_j) − molecular oxygen (O₂, X³Σ_g^-) system yielding tin monoxide (SnO, X¹Σ⁺) along with ground state atomic oxygen O(³P). The reaction can be initiated on the triplet and singlet surfaces via addition of tin to the oxygen atom leading to linear, bent, and/or triangular reaction intermediates. On both the triplet and singlet surfaces, formation of the tin dioxide structure is required prior to unimolecular decomposition to SnO(X¹Σ⁺) and O(³P). Intersystem crossing (ISC) plays a critical role in the reaction mechanism and extensively interosculates singlet and triplet surfaces. The studied reaction follows a mechanism parallel to that for the gas phase reaction of germanium and silicon with molecular oxygen, however, the presence of the tin atom enhances and expands ISC via the “heavy atom effect”.