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I've been given a very viscous liquid crystal solution and been asked for a topological scan.
With low spin-coating rates, the liquid (more like a gel) remains on the substrate and with very high spin-coating rates, the sample solidifies and the liquid crystals are no longer visible.
I am thinking of using a liquid cell, but am afraid that the solution is too viscious for it to be feasible (it is like shampoo).
Any suggestions?
Depends a bit on what the goal is. Do you want to image the top surface of your liquid crystal or do you want to image inside the solution and look at the substrate? If the top surface is the goal then I do not think you need a fluid cell.
I've been asked to image the micelles inside the solution, so not that intersted with the interaction with the substrate at all.
The worry is that since it is so viscous, the probes will get stuck, any particular probe recommended?
That is a very valid concern and might as well happen. If I encounter a case like that that I usually start with the extremes e.g. a rather stiff probe and a rather soft one to get an idea on whats going on. There might be more rational approaches but this one is quite fast. PeakForce Tapping might be a great way too if you have that mode available.
Sounds extremely challenging! Just ot clear, AFM/SPM is a surface imager. The maximum what you can do is the imaging on interfaces. We imaged the surface of liquid crystals when they grow on interfaces (Advanced Materials, 1997. 9(11): p. 917) with micellar resolution. By some reason, the best was the tapping mode with "force modulation" probes. In general, to image the surface of an interface, you will need a stable interface. This can be done by choosing an appropriate second medium and/or the probe coating. An example of well working combination would be hydrophobic surface in aqueous medium.
Best, Igor