N + 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 2 N + 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) × 10 14 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 10 8 - 10 9 cm −3 for 2 N + .