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Simulation of Imaging in Trolling Mode Atomic Force Microscopy by Molecular Dynamics Method

Abdi Nemat Abad, Ahmad | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 46952 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Nejat Pishkenari, Hossein
  7. Abstract:
  8. Atomic force microscopy (AFM), as an indispensable tool for nanoscale characterization, has major drawback for operation in a liquid environment arising from the large hydrodynamic drag on the vibrating cantilever. The newly introduced “Trolling Mode” (TR-Mode) AFM resolves this complication utilizing a specialized nanoneedle cantilever that keeps the cantilever outside of the liquid. Herein, a mechanical model with a lumped mass was developed to capture the dynamics of such cantilever with a nanoneedle tip. This new developed model was applied to investigate the effects of the needle – liquid interface on the performance of the AFM, including the imaging capability in liquid. Also nanomeniscus formation around platinum (Pt) nanoneedle partially submerged in water is simulated using molecular dynamics (MD). The contact angle and height of the meniscus are calculated using results of MD simulations. We have investigated the correlation between the tip diameter and nanomeniscus characteristics. Study of time evolution of the meniscus formation demonstrates that there are three main stages for meniscus formation depending on the contact angle between the liquid and the nanoneedle material and the potential energy changes
  9. Keywords:
  10. Molecular Dynamics ; Quality Factor ; Lumped Mass ; Atomic Force Microscopy (AFM) ; Trolling Mode Atomic Force Microscopy (AFM) ; Hydrodynamic Dissipation

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