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PeakForce QNM calibration

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a_savoini posted on Tue, Jun 21 2016 4:29 AM

Dear all, I need to study quartz samples in fluid environment in order to obtain tip-sample adhesion data, where the tip is functionalized with alkanes. My problem is the PeakForce QNM calibration. Shall I calibrate with the  functionalized or the bare tip ? Shall I calibrate in fluid  or in air ? With the relative or the absolute method ?

Thank you,


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Answered (Not Verified) Bede Pittenger replied on Mon, Aug 1 2016 5:00 PM
Suggested by Bede Pittenger

The calibration should not be affected by the functionalization unless it coats the cantilever with a relatively thick layer.  You could check by looking at the resonant frequency before and after.  Generally it is easier to calibrate in the medium that you will use to do your experiments (and deflection sensitivity must be calibrated that way), but you will sometimes find that the softer probes cannot be calibrated in liquid because the thermal peak is too low in frequency.  In that case it is best to first calibrate the deflection sensitivity and spring constant in air, add liquid, re-calibrate deflection sensitivity.  

If you are only looking for the adhesion, you do not need to use the relative or absolute method (those methods calibrate the tip radius which is needed for modulus mapping).

Hope that helps!


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Thank you !

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