The influence of imaging conditions on the appearance of lattice-resolved AFM images of mica surfaces

Abstract

The effect of imaging environments and imaging parameters on the lattice-resolved AFM images of mica surfaces has been investigated. As the force-contrast of an AFM image is determined by the tip - surface interactions, the appearance of the AFM images changes accordingly when the force applied to the tip, the scanning direction, or the imaging liquid used is changed. All these factors can modify the details of the tip - surface contact situation so as to affect both the vertical repulsive and the direction-dependent frictional forces, resulting in the superposition of local distortions and other anomalies onto the atomically resolved images of the mica surface.

Molecular Dynamics Simulation of Atomic Force Microscopy at the Water–Muscovite Interface: Hydration Layer Structure and Force Analysis

“…First, many AFM experiments of muscovite surfaces with different atmospheres show dot-like patterns in the presence of the water. The representative experiments of Liu et al using contact mode AFM demonstrated that the observed patterns varied with the overlying liquid . When n -decanol was used as the overlying liquid, the pattern was honeycomb-like, whereas the dot-like pattern was obtained with water as the overlying liquid.…”

“…We will now discuss how the simulation results will aid in interpreting AFM experiments. It has been suggested that the first hydration layer gives dot-like ,,, and honeycomb-like patterns , in AFM images. First, many AFM experiments of muscovite surfaces with different atmospheres show dot-like patterns in the presence of the water.…”

“…The representative experiments of Liu et al using contact mode AFM demonstrated that the observed patterns varied with the overlying liquid. 20 When n-decanol was used as the overlying liquid, the pattern was honeycomb-like, whereas the dot-like pattern was obtained with water as the overlying liquid. In the case of noncontact mode, Fukuma et al also observed the dotlike pattern in the cross section near the surface in the threedimensional scanning force microscope image.…”

“…Atomic force microscopy (AFM) is one of the best methods to reveal interfacial structures on solid substrates. − ,− Three-dimensional solvation structures have been revealed on the hydrophilic muscovite surface. − Because of the high lateral resolution of the technique, not only the solvation structure but also the crystal surface structure of muscovite can be obtained, and the images well reproduce the crystal periodicity. − Furthermore, previous studies have been able to show a clear lateral distribution image of adsorbed ions. − Carbon nanotube (CNT) tips have been integrated in AFM systems and show promising sensitivity for imaging with nanoscale lateral precision because of the high aspect ratio. − Although force profiles obtained by AFM reveal many interfacial properties, the force profiles are not straightforward because of the lack of a quantitative relationship between the force and the interfacial properties. Moreover, the AFM tip will inevitably displace the water of the detected area.…”

The nature of the air-cleaved mica surface

“…There are only a few AFM studies of mica cleaved and maintained in vacuum (UHV) and these investigated lateral forces and friction, and include Friction Force Microscopy (FFM) images involving stick-slip interactions, which gave insufficient resolution to distinguish the atomic lattice [39; 40]. The periodicity of the mica lattice can also be resolved in air by FFM [41; 42], and it is consistent with the expected unit cell dimensions of mica [43]. Sometimes, the very large attractive forces in air due to van der Waals and capillary interactions mean that significant damage can occur as the tip is dragged across the surface, resulting in a loss of lateral resolution.…”