| AVS 65th International Symposium & Exhibition | |
| Surface Science Division | Monday Sessions |
| Session SS+HC-MoA |
| Session: | Theory and Modeling of Surfaces and Reactions |
| Presenter: | Takat B. Rawal, University of Central Florida |
| Authors: | T.B. Rawal, University of Central Florida M. Smerieri, IMEM-CNR, UOS Genova, Italy J. Pal, University of Genova, Italy S. Hong, Brewton-Parker College M. Alatalo, University of Oulu, Finland L. Savio, University of Genova, Italy L. Vattuone, University of Genova, Italy T.S. Rahman, University of Central Florida M. Rocca, University of Genova, Italy |
| Correspondent: | Click to Email |
Elucidating the various structures involving oxygen adsorption on silver surfaces is a key issue in understanding the industrially relevant Ag oxidation process. Recently it was demonstrated that atomic oxygen can cause the extraction of substrate atoms off metal surfaces. In particular for Ag(110), the excavation process takes place already when O2 is dosed at 175 K leading, at low coverage, to the formation of single Ag vacancies [1], which can serve as reactive sites. Vacancy creation proceeds thereby via the formation of O-Ag-O complexes, which involve a local reconstruction of the surface and ignite the disruption of the Ag substrate. Here, we present details of such processes and of the various structures formed by the O adatoms at very low coverage, for some of which the energetics had already been reported in ref. [2]. To this purpose we performed scanning tunnelling microscopy experiments and density functional theory calculations. A variety of features such as isolated grey dots, sombreros, shallow grey and white structures oriented along [001] and [1-10], grey stripes, and lozenges were identified and assigned to the O adatoms in different configurations. Most of the oxygen ends up either in “zig-zag chain” or in pinned, “lozenge” shaped structures. The former interact strongly with the STM tip and are easily disrupted, giving rise to highly mobile, sombrero shaped, isolated O adatoms. Around 200 K, not only Ag vacancies are mobile with anisotropic migration rates and can merge at larger coverage into complex features, but also the mobile Ag atoms are trapped by O adatoms leading finally to the O-Ag chains oriented along [001] forming the well-known added row reconstruction.
[1] J. Pal, T. B. Rawal, M. Smerieri, S. Hong, M. Alatalo, L. Savio, L. Vattuone, T. S. Rahman, and M. Rocca, Phys. Rev. Lett., 118, 226101 (2017).
[2] T. B. Rawal, S. Hong, A. Pulkkinen, M. Alatalo, and T. S. Rahman, Phys. Rev. B. 92, 035444 (2015).
*Work is partially supported by US NSF grant CHE-1310327.