Branching ratios for electronically excited oxygen atoms formed in the reaction of N+ with O2 at 300 K

Absolute branching ratios for production of O(3P), O(1D), and O(1S) in the reaction of N+ with O2 are measured using the flowing afterglow/visible chemiluminescence technique. The O(1S) product is monitored by the O(1S)–O(1D) emission at 557.7 nm. The O(1D) product is monitored via sensitized fluorescence at 760 nm from O2(b 1Σ+g) formed by energy transfer from O(1D) to O2(X 3Σ−g). Absolute O(1D) and O(1S) yields of 70±30% and ≤0.1%, respectively, of the total atomic oxygen product are inferred by comparison to the known O(1S) and O2(1Σ+g) emission intensities from the reaction of Ar(3P) with O2. The low O(1S) yield is also obtained directly from the relative O(1S) and O2(1Σ+g) emission intensities from the title reaction. A qualitative reaction mechanism consistent with these observations is presented.