Berlin 2008 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

O: Fachverband Oberflächenphysik

O 18: Poster Session I - MA 141/144 (Atomic Wires; Size-Selected Clusters; Nanostructures; Metal Substrates: Clean Surfaces+Adsorption of Organic / Bio Molecules+Solid-Liquid Interfaces+Adsorption of O and/or H; Surface or Interface Magnetism; Oxides and Insulators: Clean Surfaces)

O 18.79: Poster

Montag, 25. Februar 2008, 18:30–19:30, Poster F

Exploring Optical Properties of MgO Films with an STM — •Hadj Mohamed Benia, Philipp Myrach, Niklas Nilius, and Hans-Joachim Freund — Fritz-Haber-Institut, Berlin, Germany

Electron injection from the tip of an STM is used to stimulate local photon emission from the surface of a thin MgO film on Mo(001). Depending on the excitation energy, several emission regimes are identified on the basis of the energy and the spatial distribution of the emitted photons. At low excitation bias, tip-induced plasmons are preferentially excited in the tip-sample gap, carrying little information on the oxide. With increasing tip bias, radiative electron transitions between field-emission resonances dominate the optical response. Their dependence on the local work function allows mapping of this quantity across the oxide film. Intrinsic optical modes of the MgO, e.g. radiative decays of excitons, are only observed when operating the STM in the field emission regime.