ATOMIC-FORCE MICROSCOPIC STUDY OF SUBSURFACE ORDERING AND STRUCTURAL TRANSFORMS IN N-ALCOHOL ON MICA AND GRAPHITE

Structure forces in n-alcohols (CnH2n+1OH (8 less than or equal to n l ess than or equal to 12)) on the mica or graphite surfaces were invest igated using an atomic force microscope (AFM). The structure force on graphite has a periodicity of similar to 0.5 nm, which is independent of temperature. The structure force on mica has a periodicity of 0.86 nm when T < 40 degrees C which increases linearly with n in the range 1.7 to 2.3 nm when T > 40 degrees C. This phase transition corresponds to a change in the alignment of molecules on the surface from paralle l (lying, at T < 40 degrees C) to normal (standing, at T > 40 degrees C).