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Issue 14, 2021
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Electron stimulated desorption of vanadyl-groups from vanadium oxide thin films on Ru(0001) probed with STM

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Abstract

Low-temperature scanning tunnelling microscopy (STM) is employed to study electron-stimulated desorption of vanadyl groups from an ultrathin vanadium oxide film. The vanadia patches are prepared by reactive vapour deposition of V onto a Ru(0001) surface and comprise a highly ordered network of six and twelve membered V–O rings, some of them terminated by upright V[double bond, length as m-dash]O groups. The vanadyl units can be desorbed via electron injection from the STM tip in a reliable fashion. From hundreds of individual experiments, desorption rates are determined as a function of bias voltage and tunnelling current. Data analysis reveals a distinct threshold behaviour with bias onsets at +3.3 V and −2.6 V for positive and negative polarity, respectively. The desorption rate varies quadratically (cubically) with the tunnelling current at positive (negative) sample bias, indicating that V[double bond, length as m-dash]O desorption is a many-electron process. Based on our findings, a mechanism for desorption is proposed that includes resonant tunnelling into anti-bonding or out of bonding orbitals, followed by vibrational ladder climbing in the binding potential of the V[double bond, length as m-dash]O ad-system. The underlying electronic states can be identified directly in the STM conductance spectra taken on the oxide surface.

Graphical abstract: Electron stimulated desorption of vanadyl-groups from vanadium oxide thin films on Ru(0001) probed with STM

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Article information


Submitted
11 Dec 2020
Accepted
03 Mar 2021
First published
03 Mar 2021

Phys. Chem. Chem. Phys., 2021,23, 8439-8445
Article type
Paper

Electron stimulated desorption of vanadyl-groups from vanadium oxide thin films on Ru(0001) probed with STM

Y. Wang, P. I. Wemhoff, M. Lewandowski and N. Nilius, Phys. Chem. Chem. Phys., 2021, 23, 8439
DOI: 10.1039/D0CP06419J

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