HIGH-RESOLUTION STM-IMAGING OF HIGHLY ORIENTED ULTRA THIN POLY(ETHYLENE) FILMS

Poly(ethylene) (PE) ultra thin films drawn from the melt have been deposited on highly oriented pyrolytic graphite (HOPG) substrates for an investigation with the scanning tunneling microscope (STM). Similar to earlier examinations of poly(1-butene) (PB-1) ultra thin films (1), the STM investigations exhibited images of PE flakes extending over some hundered nanometers. Their thickness was determined to be much larger than the normal established tunneling distance between the tip and a good conducting (metallic) sample surface. It is supposed that the STM-tip penetrates the film and reduces its thickness by scanning over the film. Thus, a destruction of the film is likely leaving only a monomolecular layer of PE macromolecules on the graphite surface. At higher resolutions an ordered structure pseudomorphic to the simple chain nature of the PE macromolecule is revealed.