Quantitative measurement of solvation shells using frequency modulated atomic forcemicroscopy

Abstract

The nanoscale specificity of interaction measurements and additional imaging capability ofthe atomic force microscope make it an ideal technique for measuring solvation shells in avariety of liquids next to a range of materials. Unfortunately, the widespread use of atomicforce microscopy for the measurement of solvation shells has been limited by uncertaintiesover the dimensions, composition and durability of the tip during the measurements, andproblems associated with quantitative force calibration of the most sensitive dynamicmeasurement techniques. We address both these issues by the combined use of carbonnanotube high aspect ratio probes and quantifying the highly sensitive frequencymodulation (FM) detection technique using a recently developed analytical method.Due to the excellent reproducibility of the measurement technique, additionalinformation regarding solvation shell size as a function of proximity to the surfacehas been obtained for two very different liquids. Further, it has been possible toidentify differences between chemical and geometrical effects in the chosen systems.