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The effect of oxygen atoms on the vibrational kinetics of CO2 and CO is studied in a DC glow discharge at reduced pressure by means of in situ FTIR spectroscopy. For this study we used two SiO2-based surface configurations: a smooth Pyrex discharge tube and a large specific surface material. The larger surface area enhances the O atom surface recombination into O2, the dominant O atom loss mechanism in our discharge conditions. The O atom density is thus reduced down to 5%–10% of the density measured with the smooth Pyrex tube, without changing significantly any other relevant plasma parameter (such as reduced electric field, gas temperature or dissociation fraction). The experimental results show a remarkable increase of the vibrational excitation of both CO2 and CO with the large surface material, i.e. low O atom density, demonstrating that atomic oxygen is a strong quencher of the vibrations of both species. In addition we show that, contrary to what could be expected, the use of large specific surfaces does not necessarily lead to lower vibrational excitation. In our experimental conditions, the possible enhanced de-excitation at the surface is compensated by the removal of oxygen atoms. Therefore these experimental results also demonstrate that large surfaces, catalytic or not, may have a significant impact on the plasma kinetics by affecting the recombination of gas phase species. [ABSTRACT FROM AUTHOR]

A detailed kinetic model for the flowing nitrogen microwave discharge and post-discharge is developed with the aim of gaining a deeper understanding into the processes responsible for the formation of the short-lived afterglow of nitrogen and for the enhancement of the concentration of [inline image] metastable, measured at approximately the same position in Sadeghi et al ( 2001 J. Phys. D: Appl. Phys. 34 1779). The present work shows that the peaks observed in the afterglow, for the density of molecules in radiative N2(B 3Πg) and [inline image] and metastable [inline image] states, can be explained as a result of a pumping-up phenomenon into the vibrational ladder produced by near-resonant V–V energy-exchange collisions, involving vibrationally excited molecules [inline image] in levels as high as v ~ 35. The present predictions are shown to be in good agreement with the measured concentrations for [inline image] metastables and N(4S) atoms, and with the emission intensities of 1+ and 1- system bands of N2. [ABSTRACT FROM AUTHOR]