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High-resolution model for noncontact atomic force microscopy with a flexible molecule on the tip apex
Journal of Physical Chemistry C
  • Chun-Sheng Guo, Key Laboratory of Advanced Technology of Materials (Ministry of Education), Superconductivity and New Energy R&D Center, Southwest Jiaotong University, Mail Stop 165#, Chengdu 610031, Sichuan, China
  • Michel Andre Van Hove, Hong Kong Baptist University
  • Xinguo Ren, Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, Anhui, China
  • Yong Zhao, School of Materials Science and Engineering, University of New South Wales, Sydney, 2052 NSW, Australia
Document Type
Journal Article
Experiments using noncontact atomic force microscopy (NC-AFM) with CO-molecule-functionalized tips have distinctly imaged chemical structures within conjugated molecules. Here we describe a detailed model based on an ab initio approach of the interaction force between the AFM tip and the sample molecule that yields atomicscale images, which agree very well with the experimental images we considered. The key ingredient of our model is to explicitly include the effect on the image due to the tilt of the CO molecule at the tip apex resulting from the lateral force exerted by the sample. On the basis of this model, we specifically discuss the distortion seen in AFM images. As reported very recently, the distortion in AFM images originates from an intrinsic effect, namely, different extents of π-electron orbitals, as well as from an extrinsic effect, specifically CO tilt. We find that intrinsic distortion is scanning height dependent, attributing to the integrated electron density in the tip−sample overlapping region moving away from (the vertical projection of) the atom or bond positions. This intrinsic distortion is dominant in AFM images, although the atomic positions could be displaced even more by the extrinsic distortion due to CO tilt.
Publication Date
American Chemical Society
Peer Reviewed
Link to Publisher's Edition
Citation Information
Chun-Sheng Guo, Michel Andre Van Hove, Xinguo Ren and Yong Zhao. "High-resolution model for noncontact atomic force microscopy with a flexible molecule on the tip apex" Journal of Physical Chemistry C Vol. 119 Iss. 3 (2015) p. 1483 - 1488 ISSN: 19327455
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