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PeakForce QNM, ScanAsyst throughput

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BrukerApplications posted on Tue, Jan 12 2010 1:50 PM

How best to optimize the scan rate for these new modes?  How fast can they go?

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Would like to know as well. I was using simple scanAsyst to scan a 50um area the velocity seemed to accelerate after a few scans. But today I'm not getting anything better than 0.1Hz.

I thought using the scanasyst air tips would be better but I'm seeing little advantage. k spring calculations don't seem to work for these.

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Andres, It sounds like you're scanning a rough sample. The ScanAsyst algorithm detects this and will lower the scan rate automatically to minimize force error. The lower limit of the algorithm is 0.1 Hz, so it seems that it has saturated. You might try reducing your scan area and see what it allows...

You should definitely use ScanAsyst Air probes. These probes have low k and work best with most samples. What issues are you having with the spring constant calculation? Are you using Thermal Tune?

Let me know,


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50um is a pretty large scan; scanning that at 1Hz results in a tip velocity of 100um/s! Slowing down to 0.1Hz brings this down to a more reasonable 10um/s. (On many samples it would not be unusual to scan 5um at 1Hz = 10um/s.) The nice thing about ScanAsyst is that it makes these corrections, and keeps you in a “safe” zone automatically.

Fritz makes a good suggestion of reducing your scan size (to effectively reduce your tip velocity). By doing this, you should get to a scan size where ScanAsyst starts to increase the scan rate. If you continue so scan smaller, the scan rate should continue to go up, but the tip velocity should remain roughly constant. Given your sample topography (and probe sharpness), this is the max tip velocity you can scan at effectively.

If this doesn’t help, can you post a good image and/or describe your sample features (material, height, and spatial frequency – ie are the variations sharp or smooth). 


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