Nitric Oxide Production from Surface Recombination of Oxygen and Nitrogen Atoms

Experimental results are presented that support the surface-catalyzed production of nitric oxide from the recombination of oxygen and nitrogen atoms on quartz. The experiments employ two-photon laser induced fluorescence detection of atomic oxygen and atomic nitrogen to characterize changes in gas-phase atom concentrations as the ratio of O to N atoms is varied at the opening of a diffusion-tube side-arm reactor. The measurements verify a correlation between decreased O-atom loss and enhanced N-atom loss in N2/N/O mixtures. Computational simulations of the side-arm reactor with a multispecies reaction-diffusion model strengthen the case for NO surface formation, reproducing observed changes in O- and N-atom concentration profiles with varying O/N ratios at the side-arm entrance when surface-catalyzed NO production is included in the boundary conditions. 2