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O: Fachverband Oberflächenphysik

O 88: Poster Session VII: Oxides and insulators: Adsorption and reaction of small molecules I

O 88.1: Poster

Donnerstag, 4. März 2021, 10:30–12:30, P

Electron Stimulated Desorption of Vanadyl-Groups from Vanadium Oxide Thin Films on Ru(0001) probed with STM — •Piotr Igor Wemhoff, Ying Wang, and Niklas Nilius — Carl von Ossietzky University, Institute of Physics, D-26111 Oldenburg,

Low-temperature STM is employed to study electron-stimulated desorption of V=O groups from a vanadium oxide film grown on Ru(0001). The film is built of an ordered network of three, six and twelve membered V-O rings, the former ones capped by upright vanadyls. These V=O groups can be reproducibly desorbed by electron injection from the STM tip. From hundreds of experiments, desorption rates are determined as a function of bias voltage and tunneling current. The rates show a threshold behavior with +3.3 V and -2.6 V bias onsets, and depend quadratically (cubically) on current for positive (negative) polarity. Apparently, V=O desorption is a multi-electron process that proceeds via resonant tunneling into bonding (anti-bonding) resonances of the V=O system followed by vibrational ladder climbing in the binding potential. The involved electronic states are identified in STM conductance spectra of the oxide surface.