EVALUATION OF MOLECULAR ARRANGEMENT IN FATTY-ACID MONOLAYERS WITH TRANSMISSION ELECTRON AND ATOMIC-FORCE MICROSCOPE

Molecular arrangements and structural defects in lignoceric and steari c acid monolayers were investigated with transmission electron and ato mic force microscopes. Lignoceric acid molecules in the monolayer, pre pared by a continuous compression method, were regularly arranged in a hexagonal array with the (10) spacing of 0.43 nm. The hexagonal array with crystallographical distortion of 4.0% was extended over 10 nm (c rystallographical continuity), and the locally disordered molecular ar rangements in the monolayer were also observed. On the other hand, ste aric acid molecules in the monolayer, prepared by a multistep creep me thod, were regularly arranged in a hexagonal array with the (10) spaci ng of 0.42 nm. The hexagonal array with the crystallograhical distorti on of 2.0% was extended over 20 nm. Distinctly disordered molecular ar rangement was not observed in the case of the stearic acid monolayer. The higher crystallographical regularity of the stearic acid monolayer might be attributed to effective sintering at interfaces among crysta lline domains during the multistep creep procedure.