Contribution of Discharge Excited Atomic N, N₂*, and N₂⁺ to a Plasma/Liquid Interfacial Reaction as Suggested by Quantitative Analysis

Abstract

Abstract Electric‐discharge nitrogen comprises three main types of excited nitrogen species‐atomic nitrogen (N atom ), excited nitrogen molecules (N 2 *), and nitrogen ions (N 2 + ) – which have different lifetimes and reactivities. In particular, the interfacial reaction locus between the discharged nitrogen and the water phase produces nitrogen compounds such as ammonia and nitrate ions (denoted as N‐compounds generically); this is referred to as the plasma/liquid interfacial (P/L) reaction. The N atom amount was analyzed quantitatively to clarify the contribution of N atom to the P/L reaction. We focused on the quantitative relationship between N atom and the produced N‐compounds, and found that both N 2 * and N 2 + , which are active species other than N atom , contributed to P/L reaction. The production of N‐compounds from N 2 * and N 2 + was enhanced upon UV irradiation of the water phase, but the production of N‐compounds from N atom did not increase by UV irradiation. These results revealed that the P/L reactions starting from N atom and those starting from N 2 * and N 2 + follow different mechanisms.