Using metallic noncontact atomic force microscope tips for imaging insulators and polar molecules: tip characterization and imaging mechanisms

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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Using metallic noncontact atomic force microscope tips for imaging insulators and polar molecules: tip characterization and imaging mechanisms
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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
Subjects:J Technologies > J990 Technologies not elsewhere classified
Divisions:College of Science > School of Mathematics and Physics
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ID Code:17694
Deposited On:17 Jun 2015 15:53

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