I assume it should be less than in ambient conditions. Since glovebox atmosphere contains trace amounts of O2 and H2O, thermodynamically the temperature needed to evaporate H2O should be less. Do you have any experience in such kind of a treatment? I prefer a little bit of precision in the answers instead of assumptions.
I have not quite understood the intention of your trance amount argument. In principle the more you have in the gas phase, the more you drive the equilibrium towards the surfaces.
With nanoporous films, capillary forces may play a big role and while not influencing te equilibrium - the time constants for reaching equilibrium may become quite substantial. And what kind of state do you want to reach? Zero monolayers of water? That requires high temperatures even in vacuum (we have metal surfaces there).
Some years back I have occasionally worked with a tempered container for sample holders which were to enter UHV. They were kept at 50-60°C to reduce desorption of Water upon insertion to the UHV (faster pump-down). For a glove box system I would target at the same kind of temperature if transfer to UHV was the purpose of getting rid of (most of) the adsorbed water.
And probably you can use the water monitor of the glove box to appreciate the progress of desorption. You could also design the heated compartment in analogy to the SAS (make it possible to be evacuated separately) and exchange N2 gas with dry one without spoiling the glove box atmosphere.
Thank you for your kind answers. My film is an oxide.
The trace amount of H2O and O2 means
You won't remove it entirely, since the water molecules love the electrostatic potential provided by the oxide lattice. That is the viewpoint of a surface scientist. Depending on what is the purpose of water desorption, you may be satisfied with just, say, 2..5 monolayersremaining... in this case I'd say 40-60°C is reasonable. Mind the time constants, though, for reaching the final state in case of strong porosity with small necks.
I see what you mean, I just found an article with a different oxide and they did a TGA study. They suggest a very long time (>16 hr 4-3% weight loss at 100 C) heat treatment under argon referring to a citation in their article. So it seems like I will likely leave my samples over night in glovebox on a hot plate. So the interplay of the surface energy and the atmosphere leads to a complex problem which does not facilitate the desorption process.
Thank you again!
I think that's a good practical idea to start with.
Slow desorption is not necessarily resulting from very complex stuff. Consider a bottle with narrow opening and compare to water in a bucket or forming a puddle. Depending on the interface area (to the gaseous phase) per liquid volume, evaporation will be faster or slower. Add capillary forces at small dimensions.
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