Atomic force microscopic (AFM) images of humic acids show discrete, globular particles, where particles of the order of magnitude 100 to 300 nm dominate the image fields; the humic acids had been grown to a steady state at pH 5.0. The AFM data are consistent with our previously reported small-angle neutron scattering (SANS) study done under similar conditions. In further agreement, the cluster-cluster interactions shown in our previous SANS study may have their counterparts in closely interacting particles appearing as twin particles in the AFM images.
Ikai, A. and Osterberg, R.
"Atomic Force Microscopy of Humic Acids,"
Scanning Microscopy: Vol. 10
, Article 3.
Available at: https://digitalcommons.usu.edu/microscopy/vol10/iss4/3