Heidelberg 2015 – wissenschaftliches Programm

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MS: Fachverband Massenspektrometrie

MS 5: Resonance Ionization

MS 5.6: Vortrag

Dienstag, 24. März 2015, 16:00–16:15, PH/HS2

Isomer-selective detection of reaction products in heterogeneous catalysis in the UHV by REMPI-ToF — •Sebastian Kollmannsberger, Andreas Winbauer, Constantin Walenta, Josef Kiermaier, Patrick Schreiber, Martin Tschurl, and Ueli Heiz — Lehrstuhl für Physikalische Chemie & Catalysis Research Center, Chemistry Department, Technische Universität München, Lichtenbergstraße 4, 85748 Garching bei München, Germany

Selective hydrogenation mechanisms in heterogeneous catalysis are of major importance for the development of new catalysts. One system of particular interest is the selective hydrogenation of unsaturated aldehydes and ketones. Many studies in this field are performed under low pressure or in vacuum and even on single crystals to ensure well defined conditions. Usually, product molecule detection in such studies is performed by EI ionization in a Q-MS due to the high sensitivity of this method. However, this technique allows only a limited discrimination between isobars, because of the unselective properties of EI ionization. In this work we present a TOF-MS in combination with laser ionization. Due to the setup, this system allows a very sensitive detection of isobaric species by different ionization wavelengths. The sensitivity is compared to a commercial EI-QMS. Furthermore, the ability of isomer-selective detection is demonstrated by the desorption of ethylbenzene and p-xylene (both C8H10) as well as of their mixtures on a Pt (111) crystal.