The Nanoscale World

force curve

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Answered (Not Verified) This post has 0 verified answers | 8 Replies | 2 Followers

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fangfang posted on Wed, Apr 27 2011 11:31 AM

I am using Dimension Icon AFM. When I am scanning a sample by ScanAsyst, the force curve will go to messy suddenly. Then I click "withdraw" and "engage" again. Sometime it will go to normal, but sometime it doesn't. Please help me, thanks!

fangfang

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replied on Wed, Apr 27 2011 6:56 PM

Hi FangFang,

It would be beneficial to know what sample you are scanning and what tip you are using. In general, if your force curve suddenly changed and does not come back to normal you may try to click "autoconfig" which is a button located in the "Force Monitor" dialog. This will force the system to recalibrate itself. There is no need to withdraw and re-engage.

Please keep us updated.

Stefan

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Top 50 Contributor
15 Posts
Points 180

Hi Stefan,

Thanks!

The sample was Silicon. The tip I used was scanasyst-air. I did try to click "autoconfig". But it didn't work.

 

fangfang

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replied on Mon, May 9 2011 10:29 AM

Hi fangfang,

That does not makes sense to me. The only thing that could may be cause it is excessive laser interference if you are e.g. aligned on a cantilever leg instead of the front.

Would you mind taking a screenshot when your force curve looks "out of shape" again and email it to me?

Thanks,

Stefan

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Top 50 Contributor
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Hi Stefan,

Sure. Please give me your e-mail address.

Fangfang

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replied on Tue, May 10 2011 10:37 AM

Sure, here we go: stefan.kaemmer at bruker-nano dot com

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Answered (Not Verified) replied on Tue, May 10 2011 12:17 PM
Suggested by Bede Pittenger

Hi Fangfang,

Thanks for sending the curve. Your foce curves show a lot of adhesion on your sample. That is why the curve is cut off at the bottom. The tip-sample adhesion simply cuases the lever to bend so much that the reflected beam that the A-B signal on the detector saturates. The only thing to avoid that is to reduce the adhesion. Is your sample static? If so then maybe ionizing the air around it and grounding might help. Otherwise you may want to use a slightkly stiffer cantilever for that sample. The strong adhesion also causes excessive ringing after pulloff. Even thiough, the PeakForce algorythm does still appear to be working fine!

Best,

Stefan

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Bruker Employee

Hi Fangfang,

Another thing that can cause large adhesion is blunt or contaminated tips.  If changing to a fresh sharp probe helps, this is probably the issue!

--Bede

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replied on Tue, May 17 2011 7:03 PM

Hi Bede,

Fangfang actually sent me an image earlier that suggested a double tip which in turn could explain the large ahesion.

Stefan

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