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P. Mesquida, D. Kohl, S. Bansode, M. Duer, G. Schitter:
"Water desorption in Kelvin-probe force microscopy: a generic model";
Nanotechnology, 29 (2018), 9 pages.

Nanoparticles or similar, nanoscale objects such as proteins or biological fibrils usually have to
be deposited from aqueous suspension onto a solid support surface for further characterization by
atomic force microscopy (AFM) and related methods such as Kelvin-probe force microscopy
(KFM). Here we show, on the examples of functionalized nanoparticles and collagen fibrils, that
water desorption after sample preparation affects their electrostatic potential determined by KFM
in a predictable manner. We explain this effect with a simple, analytical model based on the
capacitance of the partially dielectric-filled tip-sample system. We also propose practical
measures to avoid false interpretation of electrical AFM-based experiments. As the phenomenon
is very generic it may have significant implications in the application of AFM to nanoparticles
and other nanostructures including biological ones.

Kelvin-probe force microscopy, atomic force microscopy, humidity, surface charge, decay

http://dx.doi.org/10.1088/1361-6528/aae413