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Hello,
On the Nanoscope offline software I can't find the calibration parameters especially the tip radius and the spring constant after acquisition while I haven't capture force curve?
Can I change calibration parameter (tip radius, spring cste and defl sens offline after acquisition?
Also I still can't figure out how to switch from nm to nN on the map in force volume mode?
Does anybody know a good free software to extract modulus from force curve?
Sorry that's too many questions...
Thank you,
Benoit.
Hi, Benoit,
To switch from nm to nN in force volume, you should be able to do this in Commands -> set sensitivity, just update the sensitivity from nm/V to nN/V by multiplying the calibrated spring constant with the original deflection sensitivity value.
Regarding the software for analyzing force curves in force volume, there is an old post you can find here. http://nanoscaleworld.bruker-axs.com/nanoscaleworld/forums/t/761.aspx, if you already have nanoscope analysis, it already has most of the functions, there is an application note (#97) showing how to do it.
If you are using peakforce QNM to measure modulus, I am afraid you have no means to 'trace back' or 'correct' your E (modulus) by updating k (spring constant), r (stip radius) and d (deflection sensitivity). Simply because the curve fitting function E(k,r,d) is nonlinear and changing at each pixel and such functions were not recorded/saved, so were the force curves. Even though you can still update sensitivity for modulus channel under Commands, it does nothing but just multiplies a constant to your results. Thus, it will be practically important to calibrate the three parameters, especially deflection sensitivity prior to your experiment.
LA
Btw, E is especially nonliear to d, but to k and r, it can somehow be linearly corrected. And all there discussion are based on your have wrongly calibrated k, r, d as input in your file. If you didn't have calibrated d and k (r will be some default number I guess), the unit of modulus channel will be in Arb (arbitrary unit I guess), then I am not sure how this unit was calculated and is there a conversion method to unit of Pa. Maybe someone out there in the group will have better answer.
Hello Angli,
Thanks for your reply!
Actually I did calibrate the defl sens and the spring constant but I didn't measured the tip radius and I left the default value so I would like to change this default value...
For the spring constant and defl sens I just would like to access these parameter after acquisition (even if I can't change them).
Thank you.
In that case, since E is proportional to 1/sqrt(r) according to DMT model, it should be easy to update your E in filters->image math. Set Scaling Factor A to sqrt(r1/r2) and excute (r1 is the default tip radius and r2 is the calibrated tip radius).
you can access to all the parameters in file->display properties of..., both deflection sensitivity and force sensitivity are under ciao scan list.
Thank you very much for your help!!
I tried to switch from nm to nN using your method but instead of making the change on the FV channel it change on the Image channel (that switch from nm to nN). i have the choice between 2 channels in command-set sensitivity but whatever channel I update, the update is done in the image channel... i am not sure it is clear but do you have an idea what s going on?
Thanks,
Sorry for the wrong message I passed on this issue, I have checked in the latest analysis software and it seems indeed the same as what you have encountered. I guess it's a bug in the software that you update in channel 2 but the result appears in channel 1. You may wanna try other force volume analysis software or just simply change the unit in the scale bar manually using some image processing software or even in powerpoint.
Hi Benoit,
Yes, you can scale the data to compensate using image math. You cannot change deflection sensitivity though, since it is not a prefactor in the equation.Modulus is proportional to K/sqrt(R) Adhesion is proportional to K
Hello Mayur,
can you tell me exactly what I need to put in scaling factor A to correct the tip radius from default to real?
Also there is a bug in the offline software, in force volume mode I tried to switch from nm to nN in force volume channel by updating the sensitivity from nm/V to nN/V and it keep changing the scale in the image channel whatever channel I choose??