Measuring the true height of water films on surfaces

Sergio Santos, Albert Verdaguer, Tewfic Souier, Neil H. Thomson, Matteo Chiesa

Research output: Contribution to journalArticlepeer-review

43 Scopus citations


Measuring the level of hydrophilicity of heterogeneous surfaces and the true height of water layers that form on them in hydrated conditions has a myriad of applications in a wide range of scientific and technological fields. Here, we describe a true non-contact mode of operation of atomic force microscopy in ambient conditions and a method to establish the source of apparent height. A dependency of the measured water height on operational parameters is identified with water perturbations due to uncontrolled modes of imaging where intermittent contact with the water layer, or even the surface, might occur. In this paper we show how to (1)determine when the water is being perturbed and (2)distinguish between four different interaction regimes. Each of the four types of interaction produces measurements ranging from fractions of the true height in one extreme to values which are as large as four times the real height in the other. We show the dependence of apparent height on the interaction regime both theoretically and empirically. The agreement between theory and experiment on a BaF2(111) sample displaying wet and un-wet regions validates our results.

Original languageBritish English
Article number465705
Issue number46
StatePublished - 18 Nov 2011


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