Freiburg 2024 – scientific programme

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MO: Fachverband Molekülphysik

MO 17: Poster: Cold Molecules

MO 17.5: Poster

Wednesday, March 13, 2024, 17:00–19:00, Tent C

Measurement of absolute partial and total ionization cross sections of fluorine-based ozone-damaging molecules — •Mevlut Dogan, Deepthy Thomas Mootheril, Wania Wolff, Hugo Luna, Thomas Pfeifer, and Alexander Dorn — Max-Planck-Institut für Kernphysik, 69117 Heidelberg, Germany

Electron impact dissociative ionization of fluorine based molecules is studied. In existing experiments mostly relative cross sections are obtained due to the difficult determination of absolute data. We have developed a calibration procedure to convert the relative cross sections measured into absolute values. Our experiments were carried out with a Reaction Microscope. A gas mixing device was implemented to add known quantities of the target gas and a reference gas with known absolute cross section. Using this setup, we minimized calibration errors and the absolute cross-sections of fluorine-based ozone-damaging molecules were measured by electron collision from threshold to the 1keV impact energy range. The ionization cross sections of each fragment ion was measured on the absolute scale.

It has been suggested that molecules containing the CF3 group may cause fluorine-catalyzed ozone loss in the Earth stratosphere. For example, since CF3 is stable, it can destroy significant amounts of ozone via catalytic cycles involving CF3Ox radicals. Important reactions that may occur in the stratosphere are given in the literature (Scientific Assessment of Ozone Depletion, Chapter 2: Hydrofluorocarbons, 2022). Our experimental results will be compared with theoretical and experimental studies in the literature.

Keywords: absolute cross sections; fluorine-based molecules; ozone-damaging; Reaction Microscope; electron collision