SCANNING TUNNELING IMAGING OF BIOORGANIC MOLECULES AND THEIR TUNNELING PROPERTIES - FATTY-ACIDS, THEIR DERIVATIVES AND CHOLESTERYL STEARATE

Scanning tunneling microscopy imaging was applied to long-chain fatty acids, their derivatives and cholesteryl stearate in the adsorbed state at the liquid-solid interface between phenyloctane and highly oriented pyrolytic graphite. Cerotic acid, lignoceric acid, stearic acid, sodium stearate, stearoyl amide, and stearoyl anilide all produced regular arrays of dark and bright bands. Bright bands in the images of all execept the last compound were assigned as side-by-side alignment of hydrocarbon chains based on the variation of the band width between the three fatty acids. In the case of stearoyl anilide, the bright part was assigned to aromatic ring structure and the wider dark area to the hydrocarbon part.