AVS 53rd International Symposium
    Nanometer-scale Science and Technology Monday Sessions
       Session NS-MoM

Paper NS-MoM3
Chemical Specificity and Defect Characterization on MgO(001)

Monday, November 13, 2006, 8:40 am, Room 2016

Session: Nanoscale Imaging Techniques
Presenter: O.H. Pakarinen, Helsinki University of Technology, Finland
Authors: O.H. Pakarinen, Helsinki University of Technology, Finland
A. Ishiyama, Osaka University, Japan
A.S. Foster, Helsinki University of Technology, Finland
N. Oyabu, Osaka University, Japan
M. Abe, Osaka University, Japan
O. Custance, Osaka University, Japan
R.M. Nieminen, Helsinki University of Technology, Finland
S. Morita, Osaka University, Japan
Correspondent: Click to Email
MgO remains one of the most technologically essential surfaces due to its importance in catalysis. It has also been the subject of intense recent research as a substrate in nanocatalysis. Oxygen vacancies (F-centers) on the surface have been proposed to play an important role as nucleating centres for catalytic nanoparticles. Dynamic force microscopy (DFM) has the potential to image both the surface and any defects or adsorbates in atomic resolution, providing unprecedented details into surface processes. In this work we compare low temperature atomic resolution DFM imaging of the MgO (001) surface in UHV with first principles simulations of the tip-surface interaction. The comparison between theory and experiment is made possible by experimentally obtained site-specific force spectroscopy, which can be directly compared to computational predictions of the short range interaction with different tip models, therefore leading to unambiguous characterization of surface species and point defects. Tips are nanofabricated from silicon, but during DFM imaging, material is exchanged with the surface as well as with the ambient. Hence, we construct a set of probable tip models including adsorbates such as hydroxyl groups, hydrogen, magnesium and oxygen, as well as clean silicon tips. After testing imaging of a perfect area of the MgO(001) surface with two dozen most probable tip models, we establish a best fit to experiment and further simulate imaging of the characteristic defects seen on the surface in experiments.