STS curve using lock-in amplifier

Ki-Rak Kim posted on Mon, Jan 24 2011 3:02 PM

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C:\Users\Ki-Rak\Desktop\System schem.pdf

Dear all:

Now I am using scanning tunneling microscopy and added lock-in amplifier to get STS curve. I want to reduce noise and get dI/dV curve. I got some help from expert who had used STS about connection of lock-in amplified with STM system. I followed him as shown in attached pdf file, but my STM system does not work properly. I have some problem to operate STM after connection. The software (Nanoscope) always says that tip was engaged from the begining of experiment even the tip was not moved at all. When I turn the toggle switch (from Signal Access Module III, SAM III) of the 'bias' from left (input) to the right (output), the tip moves properly.

My questions are;
1) Is the connection good to use STM and STS? And can I get a dI/dV curve with this connection?
2) Why it always fails to engage the tip with toggle switch 'input'?
3) Which software should I use to get modified curve, Nonoscope or Acquire?
4) If I should use Acquire, which parameter I should choose to get dI/dV curve?
    X axis: I need bias voltage, but software has (Osc Freq, Osc Amplitude, DAC 1-4 voltage, and Digital port)
    Y axis: The need current depend on bias. But there are no current (amp).

Thank you very very much.
Regards,
Ki-Rak Kim