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Enhancing phase contrast for bimodal AFM imaging in low quality factor environments
Mehrnoosh Damircheli1, Babak Eslami2
1Department of Mechanical Engineering, Shahr-e-Qods Branch, Islamic Azad University, Tehran, Iran; Department of Mechanical Engineering, Widener University, Chester, PA, USA.
Ultramicroscopy
|May 22, 2019
Summary
This study presents a method for selecting optimal oscillation amplitudes in bimodal atomic force microscopy (AFM) when operating in liquid environments. The findings enhance phase contrast for improved material characterization of polymers.
Area of Science:
- Materials Science
- Surface Science
- Nanotechnology
Background:
- Atomic Force Microscopy (AFM) has evolved beyond topographical imaging to include material property mapping in various environments.
- Imaging in liquid environments offers realistic sample conditions but presents challenges for cantilever dynamics, especially in multifrequency AFM.
- Optimizing cantilever dynamics is crucial for enhancing signal quality in liquid-phase AFM.
Purpose of the Study:
- To provide numerical and experimental procedures for selecting oscillation amplitudes in bimodal AFM operating in liquid.
- To enhance the phase contrast using the higher eigenmode for improved material characterization.
- To validate the selected amplitude configurations through experimental verification.
Main Methods:
- Numerical simulations using van der Waals (vdW), Derjaguin-Landau-Verwey-Overbeek (DLVO), and DMT models to determine optimal oscillation amplitudes.
- Selection of amplitudes that maximize the second eigenmode's phase contrast for bimodal AFM.
- Experimental validation using polymer samples (LDPE, PS) in both air and liquid environments.
Main Results:
- The numerical procedures successfully identified optimal oscillation amplitudes for bimodal AFM in liquid.
- Simulations were performed on low-density polyethylene (LDPE), polystyrene (PS), and polytetrafluoroethylene (PTFE).
- Experimental results confirmed that the selected amplitude configurations significantly enhance the phase signal for polymer blends.
Conclusions:
- The developed procedures effectively optimize bimodal AFM operation in liquid for enhanced phase contrast.
- This method improves the capability of AFM for material compositional mapping in relevant environments.
- The study validates the utility of multifrequency AFM in liquid for advanced material analysis.
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