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MO: Fachverband Molekülphysik

MO 21: Stossprozesse, Energietransfer

MO 21.2: Poster

Thursday, March 13, 2008, 16:30–19:00, Poster C1

Electron-Exchange Parameter Measurements For Molecular Open-Shell-Targets — •Ingo Holtkötter and G. Friedrich Hanne — Physikalisches Institut, 48149 Münster, Germany

Electron collisions with simple open-shell molecules such as O₂, NO or NO₂ are important processes in both atmospheric physics and plasma chemistry. In our experiment, exchange collisions are observed directly by measuring the change of spin polarization after scattering of polarized electrons from unpolarized molecules with energies between 8 and 20eV and scattering angles up to 130^∘. Since previous experimental results and theoretical calculations with O₂ and NO as target were not in satisfactory agreement, we revived these measurements to gain deeper insight into spin-exchange effects with open shell-molecules. For NO₂, we present the first experimental results for differential elastic electron exchange scattering at low energies.

With our recent measurements, we get a detailed view of the discrepancies between the experimental and older theoretical results. New calculations for electron exchange processes with O₂ as target show a very good agreement with our data. In other cases, however, there are still discrepancies between the experimental results and theoretical calculations.

At the conference, we will present our data for the electron exchange parameter for elastic scattering of spin-polarized electrons with O₂, NO or NO₂ at energies between 8 and 20eV and compare them to available theoretical models.