Greifswald 2024 – scientific programme
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P: Fachverband Plasmaphysik
P 21: Low Pressure Plasmas and their Application II
P 21.4: Talk
Thursday, February 29, 2024, 15:00–15:15, ELP 6: HS 3
Atomic oxygen measurements with THz absorption spectroscopy, ps-TALIF, and CRDS: A comparison — Jente R. Wubs1, Uwe Macherius1, Andy S. C. Nave1, Laurent Invernizzi2, Kristaq Gazeli2, Guillaume Lombardi2, Xiang Lü3, Lutz Schrottke3, Klaus-Dieter Weltmann1, and •Jean-Pierre H. van Helden1 — 1Leibniz Institute for Plasma Science and Technology (INP), Greifswald, Germany — 2Laboratoire des Sciences des Procédés et des Matériaux (LSPM), CNRS, Université Sorbonne Paris Nord, Villetaneuse, France — 3Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e.V., Berlin, Germany
Terahertz (THz) absorption spectroscopy with quantum cascade lasers (QCLs) has recently been developed and implemented as a new diagnostic technique for investigating ground state atomic oxygen densities in plasmas. It is based on the detection of the 3P1 ← 3P2 fine structure transition at approximately 4.75 THz (i.e., approximately 63 µm). In this contribution, we will compare the results obtained with this method with those obtained by picosecond two-photon absorption laser-induced fluorescence (ps-TALIF) at 226 nm, as this is currently the most established method for measuring atomic oxygen densities, and cavity ring-down spectroscopy (CRDS) using the forbidden 1D2 ← 3P2 transition at approximately 630 nm. All measurements were performed on the same low-pressure capacitively-coupled radio frequency plasma generated in pure oxygen, for a variation of the applied power and gas pressure.
Keywords: THz absorption spectrsocopy; Atomic oxygen; Cavity ring-down spectroscopy