DETERMINATION OF THICKNESS OF HYDRATION LAYERS ON MICA IN AQUEOUS SOLUTIONS BY USING AFM

We present an experimental technique to determine the thickness of hydration layers on solid surfaces in aqueous solutions by using an atomic force microscope (AFM). This technique is based on the phenomenon where a small line bending in the AFM force–distance plot of hydrated solid surface in aqueous solutions, may be due to the existence of hydration layers on the tip and the solid surface. The thickness of hydration layers on mica plate immersed in water and NaCl solutions were determined with this technique.