AVS 52nd International Symposium
    Nanometer-Scale Science and Technology Tuesday Sessions
       Session NS+BI-TuA

Paper NS+BI-TuA6
Single Porphyrin Molecules as Information Storage Elements

Tuesday, November 1, 2005, 3:40 pm, Room 210

Session: Molecular and Biological Applications of Nanostructures
Presenter: H. Kim, Center for Science in Nanometer Scale (CSNS), Korea
Authors: H. Kim, Center for Science in Nanometer Scale (CSNS), Korea
Y. Kuk, Center for Science in Nanometer Scale (CSNS), Korea
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Redox behaviors of porphyrin molecules have been widely studied for the possible application to molecular-based information storage for two main reasons; i) they form stable radicals whose redox potentials can be tuned by the synthetic design and chelating metal ions. ii) Assembled on the substrate adequately, they exhibit considerably long charge retention times. Recently, it was shown that they can survive silicon device processing,@footnote 1@ which provides a new possibility to molecular electronics. It was, however, confirmed only for a close-packed monolayer of porphyrins to act as information storage. We separated porphyin molecules both from each other and from the substrate by making a mixed self-assembled monolayer of alkanethiol-derivatized porphyrins and alkanethiols on a Au(111) surface. Alkanethiol monolayers can act as an organic insulating layer whose resistance shows approximately exponential dependence on the chain length and the HOMO-LUMO gap is about 9eV. These properties allow us to investigate more intrinsic behaviors of organic molecules attached to alkanethiol monolayers on surface. By means of scanning tunneling microscopy and spectroscopy, we identified the porphyrin groups on the insulating alkanethiol monolayer and resolved the redox states and the charge retention time of a single porphyrin molecule. @FootnoteText@ @footnote 1@ Molecular memories that survive silicon device processing and real-world operation, Z. Liu et al., Science 302, 1543 (2003).