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P: Fachverband Plasmaphysik

P 4: Atmospheric Pressure Plasmas I

P 4.3: Vortrag

Montag, 18. März 2019, 14:45–15:00, HS 20

Formation pathways of HO₂ in a cold atmospheric pressure plasma jet investigated by cavity ring-down spectroscopy — •Sarah-Johanna Klose¹, Ansgar Schmidt-Bleker¹, Katherine Manfred², Helen Norman², Michele Gianella², Sioned Press², Grant Ritchie², and Jean-Pierre van Helden¹ — ¹Leibniz Institute for Plasma Science and Technology (INP), Greifswald, Germany — ²Department of Chemistry, University of Oxford, Oxford, United Kingdom

The kINPen, a plasma jet operated in argon, is often employed in biomedical applications, as it provides important species for the plasma to cell interaction, such as H₂O₂. In order to investigate the complex chemical reaction network of the plasma effluent, we analysed the production and destruction pathways of HO₂, which is an important intermediate in the production cycle of H₂O₂. Respective diagnostic methods, such as absorption spectroscopy, are challenging considering the small diameter of the effluent (about 4 mm). Moreover, due to their short lifetime, highly reactive species like radicals have to be measured directly in the effluent. An option to increase the optical path length through a small plasma volume is cavity ring-down spectroscopy (CRDS). We will present HO₂ densities obtained from CRDS measurements, varying the O₂ fraction in the surrounding nitrogen gas curtain. Additionally, we will show spatial distributions of HO₂, gained from Abel inversion, at different axial positions. The most important formation and destruction mechanisms of HO₂, identified by a simple reaction kinetics model, will be discussed.