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Hi,
I've been getting big scan lines across my Ti roughness characteriser sample, when I image it consistently and would like to know what could be the cause of this? I've been using the PFQNM mode in fluid and am using the Ti sample for estimating the tip diameter. To do this, I would image the Ti sample in PFQNM (fluid mode) in air, then switch over to my cells which are grown in fluid.
It would help to have an image to understand precisely what you are seeing, but it sounds as if there may be some contamination on your Ti sample. Often when a sample is immersed in water and then dried, crystals and other precipitates end up on the surface. These contaminates are usually very weakly bound to the surface and can be picked up by the tip during imaging. If that happens, a scan line will have a big step in it where the particle was picked up (or dropped). Immersing the sample again does not usually remove the contaminates.
I don't know of any way to clean the Ti sample once it has been contaminated, but perhaps someone else in teh community has tried this?
--Bede
Hi Bede,
Thanks for your reply. I don't image the Ti roughness sample in liquid, it is imaged in air. I wasn't so clear in my post.
The reason I use PFQNM in liquid mode is because right after I estimate the tip diameter using the Ti roughness sample, I switch over to imaging live cells in glass petri dishes.
Here is a link of a typical roughness image I've been getting.
http://imageshack.us/g/29/roughnessimage.png/
Regards, Warren.
Wow, those images look as if the probe and/or sample is terribly contaminated. What kind of probe is this? Do you get this when you install a fresh, unused probe and image the sample? what if you do the same with the calibration grid?
We are using ScanAsyst Fluid probes. We do get this when we install a fresh new probe; it sounds like the Ti roughness sample must be contaminated.
From your advice, it sounds like we should try to image the calibration grid with a fresh probe?
I will try to image the calibration grid as soon as I get a chance as the AFM is being moved this week.
Hi, Warren,
The image looks like raw without flattening, did you try first order flattening processing on the image?
Ang Li
Hi Ang,
Do you mean plane fit? I would plane fit it XY mode, 1st order fitting, no thresholding and then use the low pass filter on it. The scan size was increased to 2.5 um as I read in one of the Bruker manuals that a larger scan size would make it more accurate for tip qualification and so would the low pass filtering.
I guess you should try flattening (the scan lines you saw in your image should be corrected in flattening but not in plane fit), you can still use first order without threshold, no need to run low pass for this purpose.