Stuttgart 2012 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 26: Plasma-Wand-Wechselwirkung
P 26.6: Vortrag
Freitag, 16. März 2012, 15:45–16:00, V57.02
Surface vibrational relaxation of N2 studied by CO2 titration with time resolved quantum cascade laser absorption spectroscopy — •Dmitry Lopatik1, Daniil Marinov2, Olivier Guaitella2, Marko Hübner1, Yury Ionikh3, Jürgen Röpcke1, and Antoine Rousseau2 — 1INP Greifswald, Felix-Hausdorff-Str. 2, Greifswald, Germany — 2LPP, Ecole Polytechnique, Université Paris Sud-11, Palaiseau, France — 3St Petersburg State University, Institute of Physics, Ulianovskaya 1, St Petersburg, Russia
In our study a new method for the determination of the wall de-excitation probability of vibrationally excited N2 at different surfaces exposed to low pressure plasmas has been developed. A short only few ms long DC discharge pulse was applied to a mixture containing 0.05-1% of CO2 in N2 at a pressure of 133 Pa. In these low pressure conditions the main quenching process of N2(v) is heterogeneous relaxation. Due to a nearly resonant fast vibrational transfer between N2 and the asymmetric v3 mode of CO2 the vibrational excitation of these titrating molecules reflects the degree of vibrational excitation of N2. In the afterglow the vibrational relaxation of CO2 was monitored in-situ using quantum cascade laser absorption spectroscopy (QCLAS). The results were interpreted in terms of a numerical model of non-equilibrium vibrational kinetics in CO2-N2 mixtures. The values of de-excitation probability were determined for Pyrex, fused silica and TiO2 from the best agreement between measured and simulated relaxation kinetics. The effect of the CO2 admixture on the N2(v) relaxation in the gas phase and on the surface is discussed.