Time-resolved X-ray Photoelectron Spectra of Sodium Perchlorate, Sodium Chlorate and Sodium Chlorite

Abstract

Time-resolved Cl(2p), O(1s) XPS spectra of sodium perchlorate(NaClO₄), sodium chlorate(NaClO₃) and sodium chlorite(NaClO₂) were measured with a minimum measurement time of 15 minutes. For NaClO₄, Cl(Ⅶ) was reduced to Cl(−Ⅰ) via Cl(Ⅴ) by X-ray irradiation. For NaClO₃, Cl(Ⅴ) was similarly reduced to Cl(−Ⅰ) via Cl(Ⅲ) by X-ray irradiation. On the other hand, for NaClO₂, not only Cl(Ⅲ) is reduced to Cl(−Ⅰ) via Cl(Ⅰ), but also the disproportionation as 2 Cl(Ⅲ) → Cl(Ⅰ) + Cl(Ⅴ) was occurred. Simultaneously with each reduction in the solid state, the oxygen atoms bound to the chlorine atoms in the sample were oxidized to oxygen molecules by X-ray irradiation. Kinetic analysis was performed on these reactions to obtain the kinetic parameters of each reaction. The kinetic parameter of the reduction for NaClO₂ (Cl(Ⅲ) → Cl(Ⅰ)) showed the largest values.