Atomic force microscopy – A variable tool to characterize processes in the field of particle technology


Atomic force microscopy – A variable tool to characterize processes in the field of particle technology

Fritzsche, J.; Peuker, U. A.; Babel, B.; Rudolph, M.

The paper aims at giving an overview on strategies and methods applying atomic force microscopy (AFM) in various particle based processes. AFM has a wide range of applications in the field of particle technology. The typical application of the AFM is the characterization of the surface topography in the submicron range. Using the AFM in combination with the colloidal probe technique allows furthermore the direct measurement of forces acting on a particle down to atomic interactions. This enables the study of several fundamental effects on these forces.
When a liquid cell is used, the direct measurement of forces between particles surrounded by a liquid can be studied. This allows the investigation of electrostatic as well as hydrophobic and hydrophilic interactions which superimpose the van der Waals forces in liquid media. It is also possible to determine the forces acting on particles at fluid interfaces (liquid/liquid or liquid/gas) which is quite important for research e.g. in flotation or particle extraction applications.
Especially in hydrophobic systems capillary bridges due to nano-bubbles (generally gas layers) on the surfaces can occur. This bridging can be seen as an additional strong adhesive interaction mechanism leading to forces which can be orders of magnitude higher than for pure van der Waals or classic hydrophobic interactions.
The detection of nano-bubbles is possible using a combination of topography and phasecontrast scans in non-contact mode. This allows the distinction between gas and solid phases during the surface scanning. On smooth surfaces, phase contrast AFM also allows a distinction between two different solid phases, e.g. in a nano-composite material. Furthermore the combination of AFM with Raman spectroscopy superimposes the measurements of mechanical forces, topographies and detailed chemical spectral characterization. With this method local surface modification can be identified. A proper choice of tip material of the AFM (noble metal nanostructures) can even lead to the so called tip enhanced Raman spectroscopy (TERS) enabling detection of vibrational signals from a small number of molecules on a solid surface, e.g. collector molecules on mineral surfaces for flotation applications.

  • Lecture (Conference)
    Partec 2016 - International Congress on Particle Technology, 19.-21.04.2016, Nürnberg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-24709
Publ.-Id: 24709