Production of N and O atoms in flowing Ar-N_2-O_2 microwave discharges with separated N2 and O2 pulsed gases

摘要

Low frequency (a fraction of Hz) alternating pulses of N_2 and O_2 in Ar microwave plasmas are studied. From plasma emission spectroscopy, plasma electron energy is found to be enhanced during the O _2 pulse and reduced during the N2 pulse with regard to Ar plasma. After the N_2 pulse, the afterglow is produced by the recombination of N atoms. The oxygen and NO impurities are detected by NO β bands emission which follows N + O recombination. After the O_2 pulse, O atoms react with the NO impurity to produce a continuum emission. The NO impurity comes from the wall of the silica tube, probably at density levels comparable to those of N atoms as is commonly observed in the NO titration method. The interest of this NO impurity is for detection of O atoms in the afterglow.