Liquids, especially water, are the "matrices" of life and media for a large range of chemical reactions. Activities in liquid typically require three integral parts: solid species (e.g., macromolecules, cell membranes, colloidal particles, and catalytic electrodes), bulk liquid solutions, and solvation layers at liquid-solid interfaces. The liquid species, especially those in the solvation layers, play critical roles in chemical and biological activities. However, typical imaging methods, such as optical and electron microscopy, cannot resolve liquid molecules. In this talk, I will discuss our recent work on using atomic force microscopy (AFM) to probe the liquid solvation layers with 3D atomic-scale resolution at model surfaces and heterogeneous interfaces. In addition, I will describe our efforts on developing a new chemical imaging method by combining infrared spectroscopy with an aperture-based fiber probe, with the goal of label-free imaging of metabolite molecules in live cells.
