Force-deformation spectroscopy in contact mode

The deformation-distance spectroscopic curve is obtained by registering the value of the probe cantilever deflection as a function of the elongation of the piezoelectric scanner. It assumes a simple relationship in the form of Hooke’s law, linking the deformation of the lever with the amount of its deflection caused by the proximity of the probe and the sample by means of extension and compression of the tubular piezoelectric scanner. Typical curves such as those presented in the set consist of several fragments corresponding to the absence of probe-sample interaction, the jump-to-contact moment, the elastic (and possibly inelastic) deformation of the lever, and the presence of adhesive forces. On the basis of this type of relationship, it is possible to determine the real force of interaction between the probe and the sample (with additional knowledge of the force constant, which must be determined in a separate measurement, for example using the Sader method) [1]. Knowing the level of the force of interaction allows us to make the imaging results reproducible as well as to answer the question about the destructiveness of atomic force microscopy. For example, the use of "hard" probes (such as CDT-NCHR) in contact measurements results in forces of the order of tens of micronewtons, which can cause permanent deformation (scratching) of the sample surface negatively affecting the reliability of the results. The file contains 2 topographic images and 2 sets of curves.
Reference:
[1] S. B. Aksu, J. A. Turner, Calibration of atomic force microscope cantilevers using piezolevers, Review of Scientific Instruments, 78 (2007) 043704, DOI: 10.1063/1.2719649.