Defects on surfaces are thought to dominate many oxide reactions. As such, in order to fully exploit the properties of oxide surfaces, there is a need to understand the behaviour of defects. Our knowledge of point defects on TiO2(110) has been increased greatly in the past two years via a series of detailed scanning tunneling microscopy (STM) experiments. It therefore follows that non-contact atomic force microscopy (NC-AFM) images can be interpreted by comparison with STM images recorded from the same area. This can be achieved by sequentially imaging in NC-AFM then STM modes or by recording simultaneous NC-AFM and STM images.
Here, we present simultaneously recorded non-contact atomic force microscopy (NC-AFM) and scanning tunneling microscopy (STM) images of TiO2(110). The TiO2(110) surface is characterised by bridging O rows which run in the [001] direction and alternate with rows of 5-fold coordinated Ti. NC-AFM images can show these bridging O rows bright or dark depending on the tip condition [1,2]. Within both imaging regimes, point defects (assigned to oxygen vacancies and H-atoms) correlate well between the NC-AFM and STM images. However, in some cases, even when the NC-AFM showed well-resolved atomic-scale rows, the point defects were observable only in the STM images.
[1] C. L. Pang et al. Phys. Rev. B 74 (2006) 073411
[2] J. V. Lauritsen et al. Nanotechnology 17 (2006) 3436
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