A suggested mechanism for the visible chemiluminescence observed in gas phase aluminum oxidation

Abstract

A reaction mechanism that generates the excited ( A 2 Π) and/or lowest-lying 4 Σ + and 4 Π states of AlO is suggested as the source of the visible chemiluminescence often observed in the gas phase oxidation of aluminum. Data from upper atmospheric chemical release experiments utilizing aluminized grenades, aluminized burners, and trimethylaluminum appear to be inconsistent with previously proposed mechanisms, but can be reasonably accounted for by AlO ∗ pumping reactions of molecules containing loosely bound aluminum atoms with atomic oxygen. The prototype reaction Al 2 + O and Al + O 3 are discussed in some detail, in terms of the correlation of reactant and product states. According to the “electron-jump” model, the formation of excited AlO ∗ with high quantum efficiency can be expected as a consequence of the open shell structure of the aluminum oxide molecule.