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Dear AFM users,
During the YM measurements (currently im using multimode and I have hard samples) several things came up and could not exactly figure out how to handle them:
1) I tried to use the point and shoot function but the ramp and capture was not active can someone who knows how to deal this or has experienced this before please inform me how to go about it.
2)My scanned images have some line streaks going across it and so the image taken is not very good; how can I solve this problem?
3) How can you explain the difference between the modulus seen in the scale bar in the DMT channel and the one calculated from the indentation function at the post analysis stage? For a hertian fit model What criteria do i use to decide on the fit method between the contact point based and linearized model to use when evaluating YM since the values obtained are quite different?
Thank you.
Mariam
Dear Mariam,
1) This was explained here: http://nanoscaleworld.bruker-axs.com/nanoscaleworld/forums/t/1306.aspx. Basically, the answer is that you need to capture an image first (from the Point-&-Shoot menu). Once the image is captured, "Ramp and Capture" becomes enabled. According to http://nanoscaleworld.bruker-axs.com/nanoscaleworld/forums/t/1120.aspx it should be possible even after capturing optical images.
2) The line streaks are only partly avoidable. They can be caused by a bad tip, so using a new one can already solve the problem. Furthermore, you can remove them digitally, for example with the freeware software Gwyddion (http://gwyddion.net/). Also, the "Flatten" function of NanoScope Analysis can help you there.
Best regards, Dietmar
3) Unfortunately, I cannot help you with your last issue; I have to face the same problem: My QNM images often do not agree with the values calculated offline, especially when I use the "Point-&-Shoot" method. This might have to do with the different ways the data is acquired: In Point-&-Shoot mode the tip indentates the sample always with exactly the same force, while in Peak Force QNM mode there is often some Peak Force error, so the indentation force is not perfectly constant. Different indentation forces mean different deformations, means different measured modulus. Also, the total forces are different in Point-&-Shoot mode when compared with QNM mode. It might be easier to help you if you gave more detailed information on how you came to your results, and if you attached some of your results.
It would be fine to discuss that issue with some people from Bruker. I attached one of my files here:
Sah002-095_008.zip
I you compare Sah002-110 Bruch00001.008 with Sah002-110 Bruch00001.008, you will see that they give very similar Point-&-Shoot curves although they should differ strongly in their moduli according to the QNM image (3 GPa vs. 1.2 GPa). Moreover, the force curves do not agree with the Hertzian model. I use an RTESPA probe and calibrate it on a PSfoil reference sample. Has anybody got an idea how to solve these problems?
Thanks, Dietmar
Thank you for your responses Polis,