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

Early 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)