Hello Mrs. Azita Etminan

yon can see the following articles:

A Guide to AFM Sample Preparation

Part II: Sample Preparation for AFM Particle Characterization

Characterization of nanoparticles using Atomic Force Microscopy

Atomic Force Microscopes for Nanoparticle Characterization

Sample Preparation for Atomic Force Microscopes - YouTube

is there any particular reason for AFM study of nano particles?? as such, for studying topographic features of surface AFM is applicable, if nano particles are really nano in size, AFM sensitivity will be the limitation to derive any conclusions. surface of the nano particle may not be resolved .....if there is any hysteresis in the system, they appear like these kind of stacked one only, if adhesion of particles is also not good, then also the give fuzzy behaviour. so kindly check the need for doing this characteristic and invest your time and efforts...best wishes.

I think you have to control the external forces through peak force tapping mode or choice the right spot. Furthermore, you can also change integral gain, and proportional gain as well. Azita Etminan

Seniha Simale Su Uygan Thank you so much.