A Feasible SIMS Study for Characterizing Ferric Oxyhydroxides Formed on the Iron Surface Using Deuterium

Abstract

Secondary ion mass spectrometry (SIMS) has been applied to hydrogen and deuterium analysis for ferric oxyhydroxides, which is formed by reaction of an iron substrate with water; either H2 Oo r D 2O containing a small amount of sodium chloride. Mass spectra of positive and negative ions obtained by SIMS showed that deuterium in ferric oxyhydroxides can be differentiated from hydrogen, although many species of secondary ion peaks are detected. Mass spectra from an iron sample, which firstly reacted with H2O, subsequently dried and finally reacted with D2O, indicated that D2O reaches a reaction front of the iron substrate through ferric oxyhydroxides formed by reaction with H2O. This implies that the ferric oxyhydroxides formed by reaction with H2O are, more or less, porous and thus water penetrates into ferric oxyhydroxides to the substrate. These results also suggest that SIMS analysis using isotopes enable us to characterize a formation process of ferric oxyhydroxides and permeability of foreign ions in the ferric oxyhydroxides.