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Effect of Cooperative Behavior on Molecular Vibrational IETS Peak Intensities

  • Stephen L. Cunningham
  • W. Henry Weinberg
  • John R. Hardy
Part of the Springer Series in Solid-State Sciences book series (SSSOL, volume 4)

Abstract

Contrary to previous theories of the intensity of molecular vibrational energy loss peaks in IETS, we have shown that the second derivative of the tunneling current varies as n4/3 rather than linearly in n, where n is the concentration of molecules adsorbed on the insulator surface during the junction fabrication. This is a result of considering the proper form for the potential in the junction region from a layer of vibrating dipoles with all of its images. Even though obtained with a simple model for the junction, this dependence agrees with the experimental results of LANGAN and HANSMA.

Recently, LANGAN and HANSMA [1] adsorbed tritiated benzoic acid (C6H5COOH) of concentration c in aqueous solution on an aluminum oxide surface. Using a scintillation counter, they determined that the surface concentration n varied an c1.2. Separately, upon fabricating an Al-Al2O3Pb tunnel junction with benzoic acid adsorbed on the oxide surface at the Al2O3-Pb interface, they found that the intensity of an Inelastic Electron Tunneling (IET) feature at 686 cm-1 varied as c1.6 [1]. Consequently, the IET intensity varies with surface concentration as n1.3±0.1 [2].

Keywords

Brillouin Zone Adsorbate Layer Tunnel Junction Cooperative Behavior Aluminum Oxide Surface 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. 1.
    J.D. Langan and P.K. Hansma: Surface Sci. 52, 211 (1975)CrossRefGoogle Scholar
  2. 2.
    S.L. Cunningham, W.H. Weinberg, J.R. Hardy: submitted to Phys. Rev. LettersGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1978

Authors and Affiliations

  • Stephen L. Cunningham
    • 1
  • W. Henry Weinberg
    • 1
  • John R. Hardy
    • 2
  1. 1.Division of Chemistry and Chemical EngineeringCalifornia Institute of TechnologyPasadenaUSA
  2. 2.Behlen Laboratory of PhysicsUniversity of NebraskaLincolnUSA

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