Regensburg 2019 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 97: Ultrafast Electron Dynamics at Surfaces and Interfaces III
O 97.2: Vortrag
Freitag, 5. April 2019, 10:45–11:00, H16
Time Resolved Photoemission Study of the Charge Transfer Dynamics in Anatase TiO2(101) for CO Photooxidation to CO2 — •Michael Wagstaffe1, Heshmat Noei1, Simon Chung1, Lukas Wenthaus2,3, Guilherme Semione1, Steffen Palutke2,3, Giuseppe Mercurio2,3, Siarhei Dziarzhytski1, Harald Redlin1, Nicolai Klemke2, Yudong Yang2, Anne-Laure Calendron2, Franz Kärtner2, Wilfried Wurth1,2,3, and Andreas Stierle1,3 — 1Deutsches Elektronen-Synchrotron, Notkestr. 85, 22607 Hamburg, Germany — 2Center for Free-Electron Laser Science, Luruper Chaussee 149, 22761 Hamburg, Germany — 3Department Physik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
Until recently, severe limitations have been placed on understanding the behavior of the photogenerated charge carriers in the photooxidation of CO to CO2 on TiO2 surfaces due to the ultrafast nature of the reaction. With their unprecedented temporal resolution, FELs allowed new insight to be obtained that has hitherto been unattainable. By applying ultra-fast optical pump-soft X-ray probe experiments at FLASH in DESY, we have obtained first insight into the activation mechanism of CO photooxidation on anatase TiO2(101). By using an optical laser of 800 nm and a FEL energy of 647.8 eV, the changes in the Ti 2p, O 1s and C 1s core levels have been monitored on a picosecond timescale. For the first time, the photooxidation of CO to CO2 has been observed at two distinct time points of 2.1 ps and 7.3 ps, which we attribute to the charge carriers interacting with different adsorption modes of O2 on the surface.