The evidence for adsorption or incorporation of chloride ions (Cl~-) in the passive oxide film on stainless steels and Fe-Cr alloys appears to be contradictory, with some investigators reporting Cl~- in the oxide and others reporting its absence. We consider this issue by determining Cl~- adsorption and/or incorporation as a function of potential (below the pitting potential) on 316L stainless steel using X-ray photoelectron spectroscopy and compare our results to the literature on uptake of Cl~- by stainless steels and to studies on uptake of Cl~- on aluminum. The important finding is that no Cl~- is observed in the oxide film on 316L stainless steel whereas in the case of aluminum, Cl~- is incorporated into the oxide film. We present the case for those instances where Cl~- is observed in the oxide films on stainless steels and Fe-Cr alloys, these observations are a result of the experimental procedures employed.
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