Venegas de la Cerda M A, Abad J, Madgavkar A, Martrou D, Gauthier S
CEMES-CNRS, 29 rue J Marvig, PO Box 94347, F-31055 Toulouse, France.
Nanotechnology. 2008 Jan 30;19(4):045503. doi: 10.1088/0957-4484/19/04/045503. Epub 2008 Jan 4.
We present atomic resolution images of monatomic step edges on the KBr(001) surface imaged by dynamic force microscopy operated in the non-contact mode. Under certain experimental conditions, we observe a systematic and reversible change of the atomic contrast when the tip crosses the step. This change is attributed to the reversal of the polarity of the ionic tip under the influence of the tip-substrate interaction in the immediate vicinity of the step edge. This polarity reversal is attributed to a change in the atomic structure of the tip and is described by a transition between the two potential wells of a two-level system localized near the tip apex. The case of two monatomic steps imaged in succession is also investigated in detail. The results indicate that the two-level system associated with the reversal of the tip polarity involves the movement of a very limited number of ions on the tip.
我们展示了通过非接触模式操作的动态力显微镜拍摄的KBr(001)表面单原子台阶边缘的原子分辨率图像。在某些实验条件下，当探针越过台阶时，我们观察到原子对比度发生了系统且可逆的变化。这种变化归因于在台阶边缘紧邻区域的探针 - 衬底相互作用影响下，离子探针极性的反转。这种极性反转归因于探针原子结构的变化，并由位于探针尖端附近的双能级系统的两个势阱之间的跃迁来描述。还详细研究了连续成像的两个单原子台阶的情况。结果表明，与探针极性反转相关的双能级系统涉及探针上非常有限数量离子的移动。
