We worked with hydrophilized silicon wafers in AFM and SEM, see

J.M. Alonso, T. Ondarçuhu, C. Parrens, N. Górzny, A.M. Bittner, J. Molec. Liq. 276 (2019) 667-674

“Nanoscale wetting of viruses by ionic liquids“

10.1016/j.molliq.2018.12.022

Deatails for cleaning, to achieve contact angls belw 5º:

Y. Yang, A.M. Bittner, S. Baldelli, K. Kern

Thin Solid Films 516 (2008) 3948-3956

"Study of self-assembled triethoxysilane thin films made by casting neat reagents in ambient atmosphere"

Mica or glass might be more hydrophilic if cleaned very carefully. I could imagine that "doping" mica with MgCl2 (or LaCl3), which places immobile positive charges close to the surface, could be very helpful.

Mica sheet or glass would be better hydrophilic substrates.

We worked with hydrophilized silicon wafers in AFM and SEM, see

J.M. Alonso, T. Ondarçuhu, C. Parrens, N. Górzny, A.M. Bittner, J. Molec. Liq. 276 (2019) 667-674

“Nanoscale wetting of viruses by ionic liquids“

10.1016/j.molliq.2018.12.022

Deatails for cleaning, to achieve contact angls belw 5º:

Y. Yang, A.M. Bittner, S. Baldelli, K. Kern

Thin Solid Films 516 (2008) 3948-3956

"Study of self-assembled triethoxysilane thin films made by casting neat reagents in ambient atmosphere"

Mica or glass might be more hydrophilic if cleaned very carefully. I could imagine that "doping" mica with MgCl2 (or LaCl3), which places immobile positive charges close to the surface, could be very helpful.

I forgot two crucial points:

Try to find out the vapour pressure (always very difficult to find), to avoid that the IL evaporates in the SEM vacuum. Make sure that it is still a liquid, and not modified too much by the beam (e.g. by carbon deposition!) - this is even more difficult.

Generally, electron doses in the range of what is permitted for organics should be fine, but they are quite low, see

J.M. Alonso, F. Tatti, A. Chuvilin, K. Mam, T. Ondarçuhu, A.M. Bittner

Langmuir 29 (2013) 14580-14587

“The condensation of water on adsorbed viruses”

and of course for beam damage issues

R. Henderson (Nobel 2017!), Quarterly Rev. Biophys. 28 (1995) 171

Md. Abdur Rahman, unfortunately mica and glass are not suitable substrates for SEM.

Sergei Vlassov what do you mean? I have no experience with IL, but for conventional samples mica and glass are Ok (of course, with conductive coating).

Denis Korneev, if we coat the substrate, coating will change its properties, and we cannot speak about hydrophilic properties of the initial substrate anymore. So it should be reasonably conductive and hydrophilic for IL to form uniform film of IL.

Dr. Vlassov and Dr. Korneev, you are both right: Gold coatings, especially with "impure" Au of only 99.999%, or with "contaminants" like nominally 0.2 nm Ti or Cr (the usual strategy to promote Au adhesion to glass), will massively change the wetting properties, so you would loose the advantages of mica or glass.

However, with a top notch low-voltage SEM one could indeed work with pure uncoated mica or glass at low resolution (say, 5-10 nm), presumably at voltages around or below 1 kV, at very low doses. Charging will still occur, but be limited.

An alternative would be environmental SEM in water vapour, but then aggresive species like OH might react with the desired intact layer/droplets of the IL.

Another idea: STEM or TEM with a special ultrathin hydrophilic substrate, but I have no experience with that. Maybe SiO2 windows, after plasma or glow dicharge treatment?

Dr. Vlassov, thanks for the answer. Of course, coating changes the surface, then we can speak about coating properties...

Dr. Bittner, what about other metal coatings? Are they all hydrophobic for these ILs? It is possible to use a tungsten basket evaporator for many metals.

Other metal coatings: No idea, sorry.

Evaporation from a tungsten basket: I have little experience, but this should work. As mentioned, the metals should be very clean (and I guess also the basket!).