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Why the current noise increases dramatically when tip touches the sample?

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stsolong posted on Tue, Jul 24 2012 10:22 AM


I have a question concerning CAFM.

Once the tip contacts the sample surface, the current noise increases to 500pA with high sensitivity sensor. When I lift the tip up and off the surface, the current noise reduces to 2pA.

I don´t know it is normal or not. This situation does not happen for every sample.



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Top 25 Contributor
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Bruker Employee

Hi Solong,

The noise level of the module is best charicterized when the tip is off the surface. But anyway, the noise should not go up to 500 pA; is it really noise or signal. can you send me a screenshot or the original file for me to take a close look?


Chunzeng Li
Applicaiton Scientist
Nano Surfaces Division, bruker

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