Deformation, Contact Time, and Phase Contrast in Tapping Mode Scanning Force Microscopy

Abstract

The general features of tapping mode operation of a scanning force microscope are presented. Relevant factors of tapping mode such as forces, deformation, and contact times can be calculated as functions of tapping frequency, amplitude damping, and sample elastic and viscoelastic properties. Typical contact times per oscillation are about 10-7 s for hard samples and 6 × 10-7 s for soft materials, i.e., between one and two orders of magnitude smaller than their equivalents in contact mode force microscopy. The model proposed allows the determination of the phase lag between excitation signal and cantilever response. Major factors to phase contrast are viscoelastic properties and adhesion forces with little participation from elastic properties. Experiments performed on droplets of glycerin deposited on graphite illustrate the ability to image them by recording phase changes.

Force measurements with the atomic force microscope: Technique, interpretation and applications

“…An important application of Eq. (2.10) is to describe periodic excitations, F = F 0 sin vt. A periodic excitation close to the resonance frequency is the basis for non-contact (also called ''dynamic'') atomic force microscopy and for tapping mode [48][49][50]. To analyze the response of a cantilever to a periodic excitation we insert F = F 0 sin vt into Eq.…”

A New View of Electrochemistry at Highly Oriented Pyrolytic Graphite

“…The AFM phase image informs on any changes in energy dissipation during the tip-sample interaction due to changes in topography, tip-sample molecular interactions and deformation at the tipsample contact, among other factors. 43 Although difficult to interpret quantitatively, the phase angle is sensitive to changes in the local material properties and can thus provide enhanced We have shown for other carbon-based electrodes that maps of the local electroactivity of the surface correspond well to the local intrinsic conductivity of the electrode, as determined by C-AFM. 45 We thus assessed the local conductivity of HOPG, using C-AFM in air, focusing again on SPI-1 grade material, using the protocol outlined in the experimental section.…”

Effects of a slow harmonic displacement on an Atomic Force Microscope system under Lennard-Jones forces

“…The contact time t c is the time that the tip is interacting repulsively with the sample [16]. It depends on the mechanical properties of the sample and the tapping amplitude and frequency.…”