Abstract
Recent progress in frequency modulation atomic force microscopy (FM-AFM) has enabled its operation in liquid with true atomic resolution. However, the information contained in a two-dimensional height image obtained by FM-AFM is often insufficient for understanding the structures and phenomena at a solid/liquid interface. In this study, we have developed a method referred to as 3D scanning force microscopy (3D-SFM). Combined with FM-AFM, the method enables to visualize 3D distribution of water and fluctuating surface structures at solid/liquid interfaces. Here we present basic principle and applications of 3D-SFM. The 3D-SFM image obtained at a mica/water interface shows 3D distribution of the hydration layers and adsorbed water molecules with subnanometer-scale resolution. In addition, the 3D-SFM image obtained at a lipid/water interface shows 3D distribution of the fluctuating lipid headgroups.
