Berlin 2018 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 73: Surface dynamics: Reactions, elementary processes and phase transitions II
O 73.4: Vortrag
Mittwoch, 14. März 2018, 17:30–17:45, MA 043
O adatom diffusion in a dense CO matrix on Ru(0001) with video-rate variable temperature STM — •Ann-Kathrin Henß1, Philipp Messer1, Don C. Lamb1, Rolf Schuster2, and Joost Wintterlin1 — 1Chemie Department, Ludwig-Maximilians Universität München — 2Institut für Physikalische Chemie, Karlsruher Institut für Technologie
To obtain reliable kinetic parameters of surface processes it is necessary to collect data over a wide range of temperatures. For scanning tunneling microscopes (STM) this range is usually limited by the slow imaging rates. We improved a home-built beetle-type STM by modifying the scan control unit and the data acquisition system to enable video-rate STM imaging with up to 50 images per second. The STM is also equipped with a liquid helium cryostat and heating facilities, giving access to temperatures between 50 and 500 K. The combination of temperature variability and video-rate imaging allows us to monitor surface diffusion of single atoms over a much broader temperature range than before. First experiments were performed on the diffusion of oxygen adatoms in a dense layer of CO molecules on Ru(0001). Videos of the moving oxygen atoms, obtained between -50 °C and room temperature and analyzed by particle tracking, show a surprisingly complex dynamic behavior. The data provide microscopic insight into atomic transport processes on "crowded surfaces", the typical situation in heterogeneous catalytic reactions.