Different area shows different nanopore sizes, maybe due to your PES membrane is nonuniform

I think the two pictures differ because of particles size, shape, density and size distribution since these are surface morphology characterizing parameters in SEM. If you check the density they will show different density because of porosity. Again as it was coated with different size coating it may looks different. As we see the pictures one is dense and the other is having more pores. So the surface morphology definitely have different distribution of the particles even though they are from the same membrane.

Besides the things mentioned in the other answers:

The images were taken with different SEMs using different beam energy.

This may affect the contrast. The detectors seem to be ETF in both cases, but the location in vacuum chamber may be different.

> Both pictures are 2500X.

No, the magnification given in the annotation bars is different. The image sizes and especially pixel separation (45 nm (Zeiss) vs. 10 nm (FEI)) are different.

How was the coating done?

Different coatings will create different contrast. The thermal load during deposition may be different and may change the polymer. How was the layer thickness controlled?

To check the pore size:

Can you do SEM imaging with uncoated samples? Using very low current (Zeiss: aperture 10 µm or 7 µm) and low energy (Zeiss can operate below 1 kV) can give good images of polymers on conductive substrate (Al stub).

Does one of your microscopes has a low vacuum mode?

To me, they look like two different filters not the same. Besides, coating with gold or carbon is not going to make much difference in the pore size.

On a side note: I recognize one SEM image is from FEI/Thermo Fisher and the other not sure. If you use FEI SEM, make sure the magnification mode is always set the same. For some unknown reason FEI has at least three different modes to confuse the users!

I don’t know your application but would recommend trying: Millicell-24 Cell Culture Insert Plate, polyethylene terephthalate. cat# PTRP24H48.

Hope this helps,

Good luck.

As per my knowledge, the quality of SEM image depends upon the conductivity of the material. As there are two different coating materials i.e. gold and carbon, thus the difference in the images are due to the different conductivity of the gold and carbon.

Carbon coated specimen looks thermally damaged (partially melted), whether while coating, or, less likely, by electron beam. Next time when coating try to put your specimen as far as possible from source of carbon.

Vladimir Dusevich Vivek Chandel Chandrasekaran Nagaswami Stefan Baunack Solomon Hailemariam

Thank you all for answering my question. I took my sample back to the SEM. (Zeiss Gemini-300) The left picture is coated with carbon 20nm, and the right picture is coated with gold 5nm. I use the same lens (InLens), the same 10kV, the same pressure, same magnification (13000K) for the same piece of membrane. The only difference is the coating thickness.

I think the carbon coat is way too thick.

Carbon coat covers the small pores on the membrane, which shows in images that we can’t visualize the small pores and deep layers. The actual membrane pore size is bigger than 0.2uM on the surface layer base on the SEM scale, but the deep layer pores may be 0.2uM.

The manufacturer uses Phase inversion to produce the membrane. During the press and stretch process, the membrane pores get stretched which causes them to become larger and visualize like a sponge.

As mentioned earlier in this discussion: You should keep in mind that the coating itself can modify your sample, e.g. by thermal load. Did you try to get images without coating? Use very low current (smallest aperture), small beam energy.

To reduce charging you can place a TEM grid on the sample and take the image in the mesh.

Stefan Baunack I tried. however, without a coat I wasn’t able to see anything. I was thinking coat the membrane sample with Osmonium tetraxide ( maybe spell this way) or UA to see the sample. I don’t know if that is going to work .

A lot of different suggestions have been made. Perhaps the key message is to only ever change exactly ONE parameter when comparing images of different structures, as there are many (acc. voltage, current, dose, vacuum level, detector type, coating thickness, coating type...) that can influence what you see. Certainly 20nm of C coating can already start to cover many small details incl. holes that tend to be overgrown (you can buy holey C films of about 10nm thickness as TEM supports, which look a bit like the images here). Whether you use Au or C coating, my suggestion would be to coat with as low amounts as you can get away with to just avoid charging - I also assume the polymer itself will be beam sensitive so try low kV and smallest possible beam current, and then watch your specimen while scanning the beam - it may change while you watch!

Due to coating with different quantity of coated material or may be different SEM'S are used may be different voltage electron beams are used kindly change anyone parameter and again check result

would guess that the coating changed membrane surface in different way, coating alters the membrane surface, with the larger particles hiding more details of the original membrane.

In literature you can find proof that the coatings may alter the original morphology. However, these two images are acquired with very different parameters and this may also have an influence.

A scanning electron microscope (SEM) is a type of electron microscope that produces images of a sample by scanning the surface with a focused beam of electrons. The electrons interact with atoms in the sample, producing various signals that contain information about the surface topography and composition of the sample. The electron beam is scanned in a raster scan pattern, and the position of the beam is combined with the intensity of the detected signal to produce an image. In the most common SEM mode, secondary electrons emitted by atoms excited by the electron beam are detected using a secondary electron detector (Everhart–Thornley detector). The number of secondary electrons that can be detected, and thus the signal intensity, depends, among other things, on specimen topography. Some SEMs can achieve resolutions better than 1 nanometer.

It is probably due to the different between coating and non coating.

The reflection is different and performs with a different images.

I agree with all the other Answers.

when you increase the gold spectra their the material will be stable . which you can see difference as u stated in the question.

Perhaps, I would suggest to look into the impact of carriers/binders that were used as working-medium for coating processing..

May be due to the materials are different say gold and carbon and their coating thickness.

I think you coated more than needed unintentionally during carbon deposition. If your SEM is capable, you can verify at low vacuum mode so that you do not need any conductive deposition. Because, you do not need very high resolution. You can get still nice images at low vacuum mode at that magnification.

based on the information provided, the most likely explanation for the difference in appearance is the difference in the way that the gold and carbon coatings interact with the PES membrane.

Obvious point, as stated above that these images are taken with two different magnification, so it looks different. Keeping that in mind, it looks like the second image is selected from smaller features on the first image. It is just an observation at this point. Good luck.

Please check the magnification applied on both SEM image. The first image is 2.5 K, but the second is 25 K.

Here, the magnification you chose has made the main difference

Nice SEM photo's!

It looks in the SEM magnification that both SEM magnifications are not the same? The main reason for the different between the two SEM is the fact that the coating thickness is different and the type of coating is different.

I understand that you are coating the filter in order to be able to SEM them as they need to be conductive. Try to use a high power microscope ~ 1000x just to observe how the filter looks. You may learn something.