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Difference between Voltage Bias in STM/STS vs. Electrochemical Cell

  1. Jun 5, 2013 #1
    Hello Everyone,
    I am a student studying electrochemistry – specifically energy storage devices. I have been familiarizing myself with various techniques to characterize the electrode surfaces. In particular, I am interested Scanning Tunneling Microscopy (STM) / Scanning Tunneling Spectroscopy (STS).

    It appears that STM/STS can be used to measure the band-gap of semi-conductors by taking the derivative of the i-V curve in order to obtain a plot of “differential conductance” as a function of bias voltage. Where the potential region where dI/dV equals zero is taken to be the band-gap.

    Usually when I see the term “voltage”, I think of an electrochemical cell (anode, cathode, electrolyte). However, the voltage between an anode and cathode in solution is referenced to some redox couple (vs. SHE or Li/Li+ or Ag/AgCl, for example).

    In STM/STS, I know that the voltage bias is between the tip and the sample. However, no electrolyte is involved. Therefore, I cannot convert between potential scales (for example SHE => Li/Li+).

    I would like to study semi-conducing materials as potential electrodes for energy storage. However, when I apply a potential to these materials (for example to intercalate lithium) I need to know that the potential range will not be within the band-gap.

    My question is:
    How can I compare the voltage bias measured using STM/STS against the applied voltage of an electrochemical cell?

    Thanks!
    Dan
     
  2. jcsd
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