Characterization of N and O-atoms, of N\(_2\)(A) and N\(_2\)(X,v>13) Metastable Molecules and N\(_2\)+ ion Densities in Ar-N\(_2\) Afterglows Plasmas from Microwave Discharges

Abstract

The findings underscore the potential of N₂(A) and N₂+ species to enable sustainable and efficient surface treatments with applications ranging from medical devices to advanced material coatings.

Afterglow jets 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 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 x increasing from 2 to 100% at 4 Torr, 100 Watt and an afterglow time of 310^-3 s at the 5-liter reactor inlet, it is found densities in the ranges of (2-6)10¹⁴cm^-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 - 10⁹cm^-3 for N₂+.