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Browse Prior Art Database

Scanning Tunneling Microscope

IP.com Disclosure Number: IPCOM000112011D
Original Publication Date: 1994-Apr-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

McHatton, RC: AUTHOR [+1]

Abstract

Prussian Blue (PB), ferric ferrocyanide, a known semiconductor, is a mixed valence compound containing a high-spin iron (Fe3+) and a low-spin iron (FeII). The iron species can be oxidized or reduced electrochemically so that three forms of the compound exist: Prussian blue (Fe3+/II), Berlin green (Fe3+/III) and Prussian white or Everitt's salt (Fe2+/II). It has been known for more than twelve years that thin films of PB deposited on an electrode can be electrochemically oxidized or reduced in the presence of aqueous K+ [1]. The charge storage [2] and possible electron-trapping [3] properties of these films have been reported. Also, the diffusion of electrons through dry PB films on an interdigitated array electrode [4] and their use as photomemory elements [5] have been demonstrated.

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Scanning Tunneling Microscope

      Prussian Blue (PB), ferric ferrocyanide, a known semiconductor,
is a mixed valence compound containing a high-spin iron (Fe3+) and a
low-spin iron (FeII).  The iron species can be oxidized or reduced
electrochemically so that three forms of the compound exist:
Prussian blue (Fe3+/II), Berlin green (Fe3+/III) and Prussian white
or Everitt's salt (Fe2+/II).  It has been known for more than twelve
years that thin films of PB deposited on an electrode can be
electrochemically oxidized or reduced in the presence of aqueous K+
[1].  The charge storage [2]  and possible electron-trapping [3]
properties of these films have been reported.  Also, the diffusion of
electrons through dry PB films on an interdigitated array electrode
[4]  and their use as photomemory elements [5]  have been
demonstrated.

      PB's semiconducting, electron diffusion and trapping, and
photomemory properties, coupled with its three different oxidation
states, make it ideal for use as a molecular switching device.

      A thin film of PB deposited on a conducting substrate may be
electronically activated at a molecular level by a Scanning Tunneling
Microscope (STM).  The imaging properties of an STM on an atomic
level have been demonstrated [6].  The use of an STM to perform redox
(electro)chemistry in thin films has also been shown [7].

      When an STM tip, with an applied potential, is passed over the
PB film, charge can be made to build up...