Center for Functional Nanomaterials Seminar

It was recently shown that atomic resolution can be achieved in noncontact-AFM imaging of single organic admolecules by functionalizing the AFM tip with a suitable atomic termination [Gross et al., Science 325, 1110 (2009)]. In this talk, the basic principles of the technique are discussed and measurements are presented which further elucidate the mechanism underlying atomic-resolution molecular imaging and emphasize the usefulness of this new technique.
In particular, atomically resolved force map measurements on pentacene and PTCDA molecules adsorbed on Cu(111) and ultrathin NaCl films are shown. PTCDA contains oxygen heteroatoms and adsorbs in a nonplanar geometry, making it an excellent example for investigating the particular contributions of geometry and chemical composition to the contrast observed in the AFM images.
Furthermore, investigations of a beforehand unknown organic molecule, which had been extracted from a deep-sea bacterium, are presented. While analysis by mass spectrometry and nuclear magnetic resonance alone had failed to determine the exact chemical structure of the compound, the combination of the spectroscopic data with atomically-resolved AFM images and DFT calculations eventually led to the unambiguous determination of the molecular structure to be cephalandole A.