Abstract
Absolute ground-state density of nitrogen atoms N (2p(3) S-4(3/2)) in non-equilibrium Townsend dielectric barrier discharges (TDBDs) at atmospheric pressure sustained in N-2/N2O and N-2/O-2 gas mixtures has been measured using Two-photon absorption laser-induced fluorescence (TALIF) spectroscopy. The quantitative measurements have been obtained by TALIF calibration using krypton as a reference gas. We previously reported that the maximum of N (2p(3) S-4(3/2)) atom density is around 3 x 10(14) cm(-3) in pure nitrogen TDBD, and that this maximum depends strongly on the mean energy dissipated in the gas. In the two gas mixtures studied here, results show that the absolute N (2p(3) S-4(3/2)) density is strongly affected by the N2O and O-2 addition. Indeed, the density still increases exponentially with the energy dissipated in the gas but an increase in N2O and O-2 amounts (a few hundreds of ppm) leads to a decrease in nitrogen atom density. No discrepancy in the order of magnitude of N (2p(3) S-4(3/2)) density is observed when comparing results obtained in N-2/N2O and N-2/O-2 mixtures. Compared with pure nitrogen, for an energy of similar to 90 mJ cm(-3), the maximum of N (2p(3 4)S(3/2)) density drops by a factor of 3 when 100 ppm of N2O and O-2 are added and it reduces by a factor of 5 for 200 ppm, to reach values close to our TALIF detection sensitivity for 400 ppm (1 x 10(13) cm(-3) at atmospheric pressure).