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Hi all,
I have a question concerning scans on the Dimension Icon with the VITA-DM-GLA-1 tips.
I want to do scans on wood thin sections (2um), but even without heating it's very troublesome to get good topography contact scans. Due to the quite strong shift of the vertical deflection once the tip is heated, this becomes even worse when trying to get conductivity maps.
My approach so far was to heat the tip with a voltage a bit lower than the actual scan voltage, set the vertical deflection to -2V as for a standard contact mode scan, then set the intended scan voltage and approach the sample. At times it works, but soon as I have rougher sections I have big problems.
Any tipps on what to do there?
Cheers,
michael
Hi Michael,
How rough are your wood sections? what size scans are you doing? I know it can be troublesome getting good contact mode images with SThM on even slightly rough samples. Generally scanning a slow as possible helps with SThM. If you have an Icon you might try SThM in Peak Force Tapping Mode. This works, I have tried it before (attached a screenshot) although the GLA probes are fairly soft so you get a lot of ringing and adhesion depending on the sample. I tried this on the standard fibre/ epoxy sample that usually comes with the unit and it gave comparable thermal contrast images to contact mode. Maybe it will work for your sample...
Best regards
Ian
I don't think you are able to view my "cut and paste .jpg" so I uploaded to the community media
Hi Ian,
the samples are very smooth as they are cut with an ultra microtome with a fresh blade. I usually go with 5um scan size and a rate of 0.5-0.8Hz. Think I will try to lower that, maybe it helps.
Since the sections are 2um in height (and basically sharp edges) it might just be that I cannot scan those. Pity, but at least I know now that it is not just my handling.
And thanks a lot for the Peak Force Tapping suggestion, I'll try that as soon as I'm back at work. Would be really great if I can get it to work that way. Do you calibrate the tip for that (eg. deflection sensitivity). I tried that once and couldn't get a streight pull-off curve. Since I wasn't sure if that was inherent in the tip type or mine was damaged, I didn't try with another one so far as to not destroy them (I'm not in the lab for the next week, but if it helps I could upload the deflection curve once I'm back).
Best regards,
I did not calibrate the tip though I guess this could be done easily enough and added to the probe database. I just selected ScanAsyst-Air in the Setup screen as the spring constant, length etc... are fairly similar. I made sure I was using the maximum allowable amplitude in PFT (600nm peak to peak). I used the 2kHz modulation but slower would have been better. I would give it a try but if there is too much adhesion on your sample it might not work out so I would not risk damaging multiple probes over it - as they are not inexpensive probes to replace!