I want to get rid of oxidation of the mercury surface and hence using it in inert gas environment in a closed cell. But, as the mercury vapor pressure is very low I cannot go to the high vacucum regime. Thus, there is always oxygen remaining in the cell that in turn causes some oxidation, although it is quite low. Now, I want to sense and characterize the oxidised mercury interface. Can you sugest me a characterization technique that can be used to sense even an ultra-thin layer of oxidised mercury?