Advanced Instrumentation of Frequency Modulation AFM for Subnanometer-scale 2D/3D Measurements at Solid-Liquid Interfaces

Abstract Since the first demonstration of true atomic-resolution imaging by fre-quency modulation atomic force microscopy (FM-AFM) in liquid, the method has been used for imaging subnanometer-scale structures of various materials includ-ing minerals, biological systems and other organic molecules. Rencetly, there have been further advancements in the FM-AFM instrumentation. Three-dimensional (3D) force measurement techniques are proposed for visualizing 3D hydration struc-tures formed at a solid-liquid interface. These methods further enabled to visualize 3D distributions of flexible surface structures at interfaces between soft materials and water. Furthermore, the fundamental performance such as force sensitivity and operation speed have been significantly improved using a small cantilever and high-speed phase detector. These technical advancements enabled direct visualization of atomic-scale interfacial phenomena at 1 frame/sec. In this chapter, these recent ad-vancements in the FM-AFM instrumentation and their applications to the studies on various interfacial phenomena are presented.