SCANNING-TUNNELING-MICROSCOPY IMAGING OF SINGLE FLUORINE ATOM SUBSTITUTION IN STEARIC-ACID

In this paper we report on the effect that a single fluorine substitut ion in a hydrocarbon chain of stearic acid has on the molecular orderi ng of the material. and, in addition, the effect that the fluorines ha ve on the scanning tunneling microscopy (STM) contrast of an alkyl cha in physisorbed on graphite. The area demand due to a single fluorine s ubstitution is increased by only approximately 1%, demonstrating a ver y similar steric impact of hydrogen and fluorine. The required accurac y in the measurement is achieved by evaluating the moire pattern due t o the adsorbate and substrate lattices. The predicted change in the ST M contrast caused by the fluorine atom was observed for the first time .