| AVS 60th International Symposium and Exhibition | |
| Graphene and Other 2D Materials Focus Topic | Thursday Sessions |
| Session GR+AS+NS+SS-ThM |
| Session: | 2D Materials: Nanostructures |
| Presenter: | T. Risse, Freie Universität Berlin, Germany |
| Authors: | T. Risse, Freie Universität Berlin, Germany A. Gonchar, Fritz-Haber-Institut der MPG, Germany |
| Correspondent: | Click to Email |
The ideal (100) surface of MgO being the prototype of a ionic oxide is considered rather inert with respect to chemical interactions. Recent theoretical and experimental evidences show that this perception may have to be significantly altered if ultrathin films of only a few monolayer in thickness or transition metal doped systems are considered.1-3
To address these questions thin and ultrathin single crystalline MgO(100) films grown on Mo(100) were investigated. On the one hand we will discuss the properties of ultrathin MgO films between 4 and 10 ML thickness focusing on the adsorption properties of molecular oxygen. While molecular oxygen is thought to be weakly physisorbed on bulk stoichiometric MgO(100) surfaces, the stoichiometric surfaces of the thin films bind oxygen much stronger, showing a desorption only above 300 K. In addition, electron spin resonance spectroscopy done under ultrahigh vacuum conditions show that these oxygen molecules are in fact O2- radical species on the surface, being created by a charge transfer from the metal substrate onto the oxygen molecule. Spectroscopic evidence for structural modifications of the MgO surface namely polaronic distortions will be discussed.
The situation on the ultrathin film will be compared to transition metal doped MgO(100) films, which are thick enough (typically around 20 ML) to ensure that charge transfer from the metal substrate does not occur. We will discuss the geometric and electronic properties of the transition metal dopants focusing on Mo ions and discuss their impact on the redox chemistry which occurs on the MgO(100) surface.
References
[1] Hellman, A.; Klacar, S.; Grönbeck, H. J. Am. Chem. Soc. 2009, 131, 16636
[2] Frondelius, P.; Häkkinen, H.; Honkala, K. Phys. Chem. Chem. Phys. 2010, 12, 1483.
[3] Stavale, F.; Shao, X.; Nilius, N.; Freund, H. J.; Prada, S.; Giordano, L.; Pacchioni, G. J. Am. Chem. Soc. 2012, 134, 11380.