I need to measure some pores of sub-5nm size, but these membrane is fragile and can not be made sampe for TEM, also I can not see it clearly with SEM. Is there any better way to measure these holes with size below 5nm? e.g. test the ionic current through it or some other parameters
Hi Xinxin Liu
You may perform the surface area study. The BET plot will give the surface area and the BJH plot will provide the pore distribution data. From the BJH plot, you can calculate the pore size. I can suggest the above from my point of view.
Regards
Hi Xinxin Liu,
can you provide more information about your sample?
There ist a tremendous amount of experience in TEM sample preparation (e.g. https://www.springer.com/de/book/9781441959744), but also thousands of tricks, so a solution for TEM analysis may be suggested from the community.
Regards
In my opinion you have two choices.
Either you perform a surface area employing gas adsorption, and you can use BET, BJH and DFT to understand the material's pore size distribution.
Or you can prepare your sample depositing small gold layer and analyze in the SEM, with Backscattered electrons.
Xinxin Liu
There are a bunch of porosimetery techniques. Hg was used but no longer because of Hg toxicity. Take a look at this review chapter:
https://www.sciencedirect.com/topics/materials-science/porosimetry#:~:text=Porosimetry%20is%20an%20analytical%20technique,porous%20structure%20with%20increasing%20pressure
and this:
https://en.wikipedia.org/wiki/Porosimetry
Even a video on the Tube that is You:
https://www.youtube.com/watch?v=TBvt4uRndAg
Many thanks for your suggestion!
Stefan Baunack, My sample is like 5nm hole in a 40 nm thic membrame, which makes it very fragile.
Surface area analyze is a good point I would try
Gustavo Henrique de Magalhães Gomes ，the gold layer need to be very thin so not to affect the SEM measurement, which way can deposite such thin Au, maybe e-gun?
As i have read in some research paper they suggested
porosimetery which characterized porosity with 1nm size.
@Xinxin LIU
(1) I would try to transfer the membrane to a TEM grid (there are several types). Skilled TEM laboratory workers can do miracels with tweezers and a calm hand. If the membrane is too fragile for tweezers, electrostatic forces using a glass tip, a hair or an eyelash may be sufficient (the ladder a commercial products, you don't need to injure yourself). If the hand is not calm enough, a micromanipulator may help. All this stuff should be available in a TEM lab.
(2) I would expect that a 40nm membrane on a conducting support (TEM grid) could be imaged without charging effects in the TEM, may be a FEG-SEM would be sufficient.
(3) If coating would be necessary, evaporated Au would be not my 1st choice, for high resolution imaging sputtered Au-Pd, Pt, or Cr are preferred (see SEM preparation textbook by Echlin). The methods should be available in a SEM lab.
Regards
Porosimetry is one of the best option for your analysis. It can measure less than 5 nm pore size.
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