Atomic-Resolution AFM Imaging in Viscous Ionic Liquid

Abstract

Frequency modulation atomic force microscopy (FM-AFM) imaging in ionic liquids (ILs) was carried out. A quartz tuning fork sensor with a sharpened tip was used as a force sensor instead of a Si cantilever and only the tip apex was immersed in ILs. The quality factor of the sensors was kept high even in the viscous ILs, which improved the stability and the force sensitivity. Atomic-resolution topographic imaging was successfully achieved in ILs as well as in an aqueous solution. In addition, 1-dimensional force curve measurement and 2-dimensional force mapping were carried out, which revealed the interfacial structure on the IL/solid interfaces.