COLL 396 |
| Thomas Müller1, Gina M. Florio2, Markus Lackinger3, Tova L. Werblowsky1, Bruce J Berne1, and George W Flynn1. (1) Department of Chemistry, Columbia University, Havemeyer Hall, MC3138, 3000 Broadway, New York, NY 10027, (2) Department of Chemistry and the Environmental Molecular Sciences Institute, Columbia University, Havemeyer Hall, 3000 Broadway, New York, NY 10027, (3) Institute of Physics, Chemnitz University of Technology, Reichenhainer Str. 70, 09107 , Chemnitz, Germany |
| Scanning tunneling microscopy (STM) is utilized to interrogate organic molecules with extended pi-electron systems and potential applications as model systems for molecular devices. Self-assembled monolayers of chrysene and the derivatives of phthalocyanine, pentacene, and triptycene are generated using vapor deposition and investigated in situ at low temperature. High-resolution STM images permit the determination of crystallographic monolayer parameters and molecular orientation, thus giving insight into the interactions driving the self-assembly process. The submolecular image contrast exhibits a pronounced dependence on bias voltage polarity, i.e., on accessing occupied versus unoccupied sample states. Electronic structure calculations performed for isolated molecules show that the observed intramolecular structure can be understood in terms of resonant tunneling mediated by molecular orbitals. Correspondingly, single point tunneling spectra show a distinct signature of the organic adlayer as expected for resonant tunneling, thereby providing information about the electronic structure of the surface-bound species. |
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Nanoscience and Nanotechnology
8:30 AM-11:45 AM, Wednesday, March 31, 2004 Marriott -- Orange County 5, Oral
Division of Colloid and Surface Chemistry |