DIRECT OBSERVATION OF MOLECULAR ARRANGEMENTS IN FATTY-ACID MONOLAYERSWITH AN ATOMIC-FORCE MICROSCOPE

Molecular-resolution images of fatty acid molecules in the monolayers on mica substrate were successfully observed with an atomic force micr oscope (AFM) for the first time. The AFM image of a lignoceric acid mo nolayer prepared at a surface pressure of 5 mN-m-1 showed a two-dimens ional periodic structure with locally disordered molecular arrangement s. Also, the nondestructive AFM image observation was successful for a stearic acid monolayer which was prepared by a multistep creep method , indicating that a high mechanical stability of the monolayer is inev itably required for the nondestructive AFM observation.