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Sequential STM images of FAPPB/R1ATC9 obtained at alternating sample biases of +1.0 and -1.0 V. The majority of the FAPPB molecules (apparent protrusions, displayed as bright spots) switch conductance states between OFF at +1.0 V and ON at -1.0 V sample bias. The red and green boxes follow one FAPPB molecule that exhibits this bias dependence. Imaging conditions: 4000 ‰ Ч 4000 ‰, I = 2 pA.
A paper describing the research results, titled "Molecular Engineering of the Polarity and Interactions of Molecular Electronic Switches," will be published in the Journal of the American Chemical Society on 21 December 2005. "This research confirms our hypothesis of how single-molecule switches work," says Penn State Professor of Chemistry and Physics Paul S. Weiss, whose lab tested the molecules. "Molecular switches eventually may become integrated into real electronics, but not until after someone discovers a way to wire them." In addition to Weiss, the research team includes Penelopie Lewis of Penn State, who now is at Columbia University; James Tour and Francisco Maya at Rice University; and James Hutchison and Christina Inman at the University of Oregon.