Determination of N and O‐atoms and N2 (A) Metastable Molecule Densities in the Afterglows of N2‐H2, Ar‐N2‐H2 and Ar‐N2‐O2 Microwave Discharges

Abstract

AbstractEarly afterglows of N2‐H2, Ar‐N2‐H2 and Ar‐N2‐O2 flowing microwave discharges are characterized by optical emission spectroscopy. The N and O atoms and the N2 (A) metastable molecule densities are determined by optical emission spectroscopy after calibration by NO titration for N and O‐atoms and measurements of NO and N2 band intensities. If an uncertainty of 30% is estimated on N‐atomic density, an inaccuracy of one order of magnitude is obtained on the O and N2 (A) densities. In N2‐(0.05‐2.5%)H2 and Ar‐(1‐50%)N2‐(0.05‐2.5%) H2 gas mixtures, the O‐atoms are coming from O2 impurities in the discharge. Concentrations of N and O‐atoms and of N2 (A) densities are compared to the ones obtained in Ar‐(5‐50%)N2‐(0.2‐2.5%) O2 gas mixtures in which a controlled amount of O2 is added. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)