Experimental study of surface contributions to molecule formation in a recombining N2/O2 plasma

R a B Zijlmans (1) , S Welzel (2) , O Gabriel (3) , G Yagci (1) , J H van Helden (4) , J Röpcke (2) , D C Schram (1) , R Engeln (1)

1 Department of Applied Physics [Eindhoven]
2 INP - Leibniz Institute for Plasma Science and Technology
3 HZB - Helmholtz-Zentrum Berlin für Materialien und Energie GmbH = Helmholtz Centre Berlin for Materials and Energy = Centre Helmholtz de Berlin pour les matériaux et l'énergie
4 The Physical and Theoretical Chemistry Laboratory

A low pressure recombining Ar plasma to which mixtures of N 2 and O 2 were added has been studied to explore the relevance of surface related processes for the total chemistry. The abundances of the stable molecules N 2, O 2, NO, N 2 O and NO 2 have been measured by means of a combination of infrared tunable diode laser absorption spectroscopy and mass spectrometry. A gas phase chemical kinetics model was developed in chemkin to investigate the contribution of homogeneous interactions to the conversion of the feedstock gases N 2 and O 2. At a partial pressure of N 2 plus O 2 less than 8 Pa, significant discrepancies between measured and calculated concentrations of N 2 O and NO 2 were observed, indicating that heterogeneous processes are dominating the chemistry in this pressure range. At a partial pressure of N 2 plus O 2 higher than 40 Pa and a relatively high fraction of admixed O 2 we observed a fair agreement between measured and calculated concentrations of NO molecules, indicating that homogeneous processes (notably Natom induced) are more dominant than heterogeneous processes.

Mots clés: 52.50.Nr; 52.70.Kz; 82.33.Xj; 52.40.Hf

R a B Zijlmans, S Welzel, O Gabriel, G Yagci, J H van Helden, et al.. Experimental study of surface contributions to molecule formation in a recombining N2/O2 plasma. Journal of Physics D: Applied Physics, 2010, 43 (11), pp.115204. ⟨10.1088/0022-3727/43/11/115204⟩. ⟨hal-00569261⟩