AFM topography images
Atomic Force Microscopy (AFM) is a powerful tool that provides information on surfaces reactions to the contacting fluid by measuring surface forces at nano-scale in air and liquid environments, in addition to high resolution surface topography characterization. My PhD project was benefited from using of such advanced technique to measure the interaction between two calcite surfaces in salt solutions. You can read more about this work in one of my published atricles  or my PhD thesis  . There are several articles focused on how the AFM and force measurement techniques work, e.g.  and . To summarize, an AFM uses a cantilever (with micrometer size), typically with a sharp tip to scan over a surface. A laser beam is used to detect the cantilever deflection as the tip approaches the surface. Attractive forces at the small separation between the tip and the sample surface cause cantilever deflection towards the surface. Computer analysis of the cantilever deflection provide detailed information on the surface topography and its reaction to the cantilever tip and its environement.
The left image shows (top): surface of a small calcite fragment (used for one day of experiment, for force measurements, during my PhD) in salt (MgSO4) solution. (Bottom): surface of a deposited calcite using ALD (Atomic layer Deposition) method  used for one of our SFA force measurements. This image provides detailed information on surface roughness that may influence the measured interaction forces.