In 1997 we showed that hexadecylquinolinium tricyanoquinodimethanide is a unimolecular rectifier, by scanning tunneling microscopy and also as a Langmuir-Blodgett (LB) monolayer, sandwiched between Al electrodes. We have now seen rectification in a new molecule: this rectification can be followed both by conventional current-voltage curves and also by second harmonic detection at 4.2 K of a broad signal, at the same bias as at room temperature, because at forward bias the current is transferred elastically from metal electrode to the lowest unoccupied orbital of the molecule. The same spectrum also shows inelastic electron tunneling due to CH2 vibrations (the dominant feature) and a strong zero bias anomaly (ZBA).

Robert Metzger
Professor, Department of Chemistry,
University of Alabama
B.A., 1962, University of California, Los Angeles
Ph.D., 1968, California Institute of Technology
Postdoctoral Research Associate, 1969-1971, Stanford University.

Northwestern University NCN Student Leadership Council
Network for Computational Nanotechnology

Researchers should cite this work as follows:

• Robert Metzger, NCN at Northwestern University (2007), "Orbital Mediated Tunneling in a New Unimolecular Rectifier," https://nanohub.org/resources/2748.

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1. devices
2. molecular electronics
3. nanoelectronics
4. nanowires
5. quantum transport
6. scanning probe microscopy (SPM)
7. surfaces