Graduate School of Engineering, Osaka University, 2-1 Yamada-Oka, Suita, Osaka 565-0871, Japan.
Nanotechnology. 2010 Apr 23;21(16):165702. doi: 10.1088/0957-4484/21/16/165702. Epub 2010 Mar 26.
The TiO(2)(110)-(1 x 1) surface is investigated using non-contact atomic force microscopy (nc-AFM) at 80 K. We successfully obtained a distinct type of image contrast mode which does not exhibit hydroxyl (OH) impurity defects that mostly appear in common nc-AFM images. We named the obtained distinct type of image contrast as the 'hidden mode'. The assignments of surface atomic rows in this contrast mode are not easy in the absence of defects. By recording different contrast modes in the same region of the surface, we identified the atomic rows obtained in the 'hidden mode' image contrast as bridging oxygen atoms (O(b)). The mechanism of contrast formation was attributed to tip-induced displacement of H atoms over oxygen atoms in the OH groups on the O(b) rows. This interpretation was supported by dissipation measurements. A possible candidate for the tip-generating hidden-mode image contrast was interpreted to be a positively terminated tip apex with a dimer-like structure, revealing an attractive interaction with oxygen and a repulsive force on H atom sites. In addition, with a different tip state at close tip-sample distances, we were able to successfully resolve a high resolution image of the in-plane oxygen atoms.
使用非接触原子力显微镜（nc-AFM）在 80 K 下研究 TiO(2)(110)-(1 x 1) 表面。我们成功获得了一种独特的图像对比模式，该模式不显示羟基（OH）杂质缺陷，这些缺陷通常出现在常见的 nc-AFM 图像中。我们将获得的独特图像对比模式命名为“隐藏模式”。在没有缺陷的情况下，这种对比模式中表面原子行的分配不容易确定。通过在表面的同一区域记录不同的对比模式，我们确定了在“隐藏模式”图像对比中获得的原子行是桥氧原子（O(b)）。对比形成的机制归因于尖端诱导 OH 基团中氧原子上 H 原子的位移。耗散测量支持了这一解释。对于尖端产生隐藏模式图像对比的可能候选物，解释为具有二聚体样结构的带正电的尖端顶点，揭示了与氧的吸引力和对 H 原子位置的排斥力。此外，通过在接近尖端-样品距离的不同尖端状态，我们能够成功解析出平面氧原子的高分辨率图像。
