Gao, David Zhe, Grenz, Josef, Watkins, Matthew , Canova, Filippo Federici, Schwarz, Alexander, Wiesendanger, Roland and Shluger, Alexander L. (2014) Using metallic noncontact atomic force microscope tips for imaging insulators and polar molecules: tip characterization and imaging mechanisms. ACS Nano, 8 (5). pp. 5339-5351. ISSN 1936-0851
Full content URL: http://pubs.acs.org/doi/abs/10.1021/nn501785q
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Item Type: | Article |
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Item Status: | Live Archive |
Abstract
We demonstrate that using metallic tips for noncontact atomic force microscopy (NC-AFM) imaging at relatively large (>0.5 nm) tip-surface separations provides a reliable method for studying molecules on insulating surfaces with chemical resolution and greatly reduces the complexity of interpreting experimental data. The experimental NC-AFM imaging and theoretical simulations were carried out for the NiO(001) surface as well as adsorbed CO and Co-Salen molecules using Cr-coated Si tips. The experimental results and density functional theory calculations confirm that metallic tips possess a permanent electric dipole moment with its positive end oriented toward the sample. By analyzing the experimental data, we could directly determine the dipole moment of the Cr-coated tip. A model representing the metallic tip as a point dipole is described and shown to produce NC-AFM images of individual CO molecules adsorbed onto NiO(001) in good quantitative agreement with experimental results. Finally, we discuss methods for characterizing the structure of metal-coated tips and the application of these tips to imaging dipoles of large adsorbed molecules. © 2014 American Chemical Society.
Keywords: | Atomic force microscopy, AFM, Imaging mechanism, insulator, Metallic tips, NC-AFM, Molecules, JCOpen |
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Subjects: | J Technologies > J990 Technologies not elsewhere classified |
Divisions: | College of Science > School of Mathematics and Physics |
Related URLs: | |
ID Code: | 17694 |
Deposited On: | 17 Jun 2015 15:53 |
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