Applications of Atomic Force Microscopy to Surface Investigations in Liquids

Atomic force microscopy (AFM) using frequency modulation (FM) detection has been widely used for the atomic scale investigations of various materials. However, high-resolution imaging in liquids by FM-AFM is severely hindered by the extreme reduction of the Q-factor due to the hydrodynamic interaction between the cantilever and the liquid. Recently the use of the small amplitude mode and the large noise reduction in the cantilever deflection sensor brought a great progress in FM-AFM imaging in liquids. In this article the details of the problems in FM-AFM imaging in liquids as well as the general directions of the improvements are described. The present status of the high-resolution FM-AFM imaging is also presented. Furthermore, future prospects and possible applications of FM-AFM in liquids are discussed.