Determination of N and O-Atoms, of N2(A) and N2(X, v > 13) Metastable Molecules and N2+ Ion Densities in the Afterglows of Ar-N2 Microwave Discharges

Early afterglows of Ar-N2 flowing microwave discharges are characterized by optical emission spectroscopy. The N and O atoms, the N2(A) and N2(X, v > 13) metastable molecules and N2+ ion 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. For an Ar-xN2 gas mixture with × increasing from 2 to 100% at 4 Torr, 100 Watt and an afterglow time of 3 × 10- 3 s at the 5 liter reactor inlet, it is found densities in the ranges of (2 - 6) × 1014 cm- 3 for N-atoms, one order of magnitude lower for N2(X, v > 13) and for O-atoms (coming from air impurity), of 1010 - 1011 cm- 3 for N2(A) and of 108 - 109 cm- 3 for N2+.