Dresden 2006 – wissenschaftliches Programm
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O: Oberflächenphysik
O 29: Poster session II (Nanostructures, Magnetism, Particles and clusters, Scanning probe techniques, Time-resolved spectroscopy, Structure and dynamics, Semiconductor surfaces and interfaces, Oxides and insulators, Solid-liquid interfaces)
O 29.73: Poster
Mittwoch, 29. März 2006, 14:30–17:30, P2
Growth, atomic structure and vibrational properties of thin MnO films on Pt(111) — •Steffen Sachert1, Christian Hagendorf1, Krassimir Kostov2, and Wolf Widdra1 — 1Martin-Luther-Universität Halle-Wittenberg, FB Physik, D-06120 Halle (Salle) — 2Institute of General and Inorganic Chemistry, Bulgarian Academy of Science, BG-1113 Sofia
Thin MnO layers (from 0.2 to 4 monolayers) have been grown on Pt(111) by reactive deposition of Mn in an O2 atmosphere. High-resolution electron energy loss spectroscopy (HREELS), low energy electron diffraction (LEED) and variable-temperature scanning tunneling microscopy (STM) have been used to investigate surface vibrational and structural properties of various thin manganese oxide films.
Submonolayer coverages of MnO grown at 375 K are characterized by strong Fuchs-Kliewer phonons. The corresponding MnO coverages within the monolayer are estimated by CO adsorption at 85 K and thermal desorption. For the completed MnO monolayer on Pt(111) a well-ordered (19×1) superstructure is observed in LEED and in atomically resolved STM. The related HREEL spectrum shows a narrow Fuchs-Kliewer phonon at 365 cm−1.
Further growth of MnO occurs layer-by-layer as found by STM. The layer-dependent vibrational properties and their changes with annealing to higher temperatures will be discussed: Heating the films to 700 K improves ordering in the 2D film. At 800 K, annealing leads to the well-defined monolayer with few, larger 3D MnO clusters, whereas at about 1100 K alloy formation takes place.