Mechanical properties of the nanoscale molecular cluster of water meniscus by high-precision frequency modulation atomic force spectroscopy

The mechanical properties (viscoelasticity) of the nanoscale molecular cluster of water meniscus, spontaneously formed between a quartz tip (∼ 100 nm curvature) and a mica substrate were quantitatively studied. The theoretical and experimental investigation was performed on the basis of the quartz tuning fork-based frequency modulation-atomic force microscope system with a high vertical resolution (∼ 0.5 Å). The proposed system is suitable apparatus for the dynamic force spectroscopy of nanoscopic materials with several advantages including high sensitivity, short response time, immunity to the electrical noise, and simple and intuitive interpretation of the results using the frequency shift.