Dresden 2017 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

O: Fachverband Oberflächenphysik

O 31: Oxide and Insulator Surfaces: Structure, Epitaxy and Growth I

O 31.3: Vortrag

Dienstag, 21. März 2017, 11:00–11:15, WIL C107

Structure of ultra-thin ZnO films supported on Ag(111) characterized by IR spectroscopy — •Xiaojuan Yu, Alexei Nefedov, Yuemin Wang, and Christof Wöll — Institute of Functional Interfaces, Karlsruhe Institute of Technology, 76344, Eggenstein-Leopoldshafen, Germany.

The importance of thin oxide layers on the surface of metals under reaction conditions has already been pointed out in many contexts. The particular interest in ZnO films has recently been reinforced due to the observations of interlayer structural relaxations resulting in depolarized graphitic structures. Here, we report a thorough study of CO absorption on a Zn/Ag alloy single-crystal substrate (Ag/Zn ratio 9:1) subjected to different oxidation procedures using primarily infrared reflection absorption spectroscopy (IRRAS) in conjunction with XPS, LEED and DFT calculations. The evolution of ZnO thin films on Ag(111) is monitored by IRRAS using CO as a probe molecule. The results show a typical CO band at 2160 cm-1 that shifts to 2178 cm-1 with decreasing the coverage. This frequency is slightly lower than those observed for wurtzite ZnO bulk but significantly different from ZnO thin films formed on Cu(111). In the later case, a huge red shift around 70 cm-1 relative to wurtzite ZnO was detected due to strong interactions between ZnO and the supporting metal. Based on the DFT calculations, we propose that the Zn and O atoms are arranged in planar sheets like in the hexagonal boron-nitride prototype structure, in accord to previous results.