Mapping Electrostatic Forces Using Higher Harmonics Tapping Mode Atomic Force Microscopy in Liquid
| Autor: | Bart G. de Grooth, Kees van der Werf, S. John T. van Noort, Jan Greve, O.H. Willemsen |
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| Rok vydání: | 1999 |
| Předmět: |
Kelvin probe force microscope
Chemistry Electrostatic force microscope METIS-128428 Atomic force acoustic microscopy Charge density Surfaces and Interfaces Conductive atomic force microscopy Condensed Matter Physics IR-59427 Electrochemistry Harmonic General Materials Science Atomic physics Non-contact atomic force microscopy Spectroscopy Harmonic oscillator |
| Zdroj: | Langmuir, 15(21), 7101-7107. American Chemical Society Langmuir, 21, 7101-7107. American Chemical Society |
| ISSN: | 0743-7463 |
| Popis: | A simple model of a damped, harmonic oscillator is used to describe the motion of an atomic force microscope cantilever tapping in fluid. By use of experimentally obtained parameters, excellent agreement is found between theory and experimental results. From the model we estimate that the force applied on the sample can range up to 100 nN, depending on the surface charge density. Detailed analysis of the cantilever deflection reveals subtle differences in the oscillatory motion, as a result of differences in the tip-sample interaction, which can conveniently be visualized by spectral analysis. The amplitudes of the higher harmonic frequencies are shown to be sensitive for electrostatic interactions. Mapping of higher harmonic amplitudes is applied to qualitatively map the surface charge density of DNA molecules on poly-L-lysine coated mica. |
| Databáze: | OpenAIRE |
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