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Dear community,
I have serious problems verifying my PeakForce QNM images. In order to prove the modulus and adhesion maps I got, I decided to do Point-&-Shoot measurements of the respective hard and soft (or sticky and non-sticky) areas. That way I wanted to show the different moduli and adhesion properties as force-distance curves. The problem is that the single force curves absolutely don't agree with the property maps.
I added a MCA file to this post (just unpack the .zip folder and open the .mca file in it with NanoScope Analysis). As you can see the marked points are at positions with very different DMTModulus and very different Adhesion. However, as you plot the force-distance curves you will see that the moduli are basically equal and the adhesion is actually highest it the area where the machine detected the lowest one in the PeakForce QNM measurement.
Could that be a sign that the property maps are just artifacts that disappear as soon as you measure at low frequency?
Thanks a lot in advance. Hope you can help me!
Dietmar
Sah002-095_008.zip
Hello Polis,
I really had a good look at your files this weekend, but I am afraid I can not really help you. If I look at the scale's in the adhesion graph it is exactly the same as the adhesion's measured with "point and shoot". If it is flipping around as you claim, I can not see. The part were you do you point and shoot is on such a small part of the picture, it is impossible for me to find the exact place in the normal scan.
If you want to compare, you should make a picture much more zoomed in, I think....
But I think that the "Harmonix callibration sample" in the PeakForce QNM sample kit is much easier to check, I would start there.
Best regards,
Joop
I will try that. Thank you; hope it works.
PFQNM ramping speeds are about 2000 times faster than Point & Shoot ramping speed. How can you even think of comparing them? If you to compare force curves with PFQNM data, you need the PeakForce Capture option.
If you cannot verify the PFQNM images with slower measurements, you can assume that they are artifacts. PF Capture wouldn't help as it scans with the same speed and might therefore be affected by the same artifacts.
Anyway, I made some highly magnified scans that showed that the scan speed had no influence on these images. You can find additional information here: http://dx.doi.org/10.1016/j.polymer.2014.06.030