The passage of negatively charged ions through a thin metal wall

[mconnelldouglas]

Assume a few mm-thick aluminium wall behind which is placed some number of negatively charged oxygen molecules. (The diameter of oxygen molecule is lower than a distance between atoms of solid aluminium)

Is it possible for an external electric field to make those ions infiltrate through the wall?

If yes, how to calculate the strength of such electric field?

 

[Baluncore]

Welcome to PF.

(The diameter of oxygen molecule is lower than a distance between atoms of solid aluminium)

It is NOT possible for oxygen gas to diffuse through solid aluminium metal. The space between the nuclei of aluminium metal is filled with shared free electrons. You need to consider the ionic radius of Al, rather than the separation of nuclei in the crystal lattice.

When oxygen contacts aluminium, it immediately reacts to form sapphire, Al₂O₃. That locks the surface and prevents more oxygen entering the Al metal.

Is it possible for an external electric field to make those ions infiltrate through the wall?

No, well not unless the Al metal is torn apart by the electric field. Then you will have a plasma of ionised aluminium and oxygen atoms.