A novel method for measuring the surface coverage of randomly distributed
cylindrical nanoparticles such as nanorods and nanowires, using atomic force
microscopy (AFM), is presented. The method offers several advantages over
existing techniques such as particle beam and x-ray diffraction spectroscopy.
These include, subnanometer vertical and lateral resolution, non destructive
interaction with the sample surface allowing repeated measurements,
user-friendly setup and ambient operating conditions. The method relies on the
use of a statistical model to describe the variations of the nanoparticles
aggregates height as a function of x,y position on the sample surface measured
by AFM. To verify the validity of the method we studied two types of randomly
oriented networks of carbon nanotubes (CNTs) and silver nanowires (Ag NWs) both
processed from solution phase. Experimental results are found to be in
excellent agreement with model predictions whilst analysis of the measured
surface height density, together with the nanoparticle diameter statistical
distribution, allow the extraction of the coverage coefficients for all
detected nanoparticle aggregates as well as for the total surface coverage. The
method can be seen as a new powerful tool for the quantitative surface coverage
analysis of arbitrary nanoscale systems.