A novel method for the study of the effects of Cl- ions on passivation using the Cl36 radioisotope

This paper reports on a method developed for the in-situ investigation of the interactions of Cl- with metal surfaces. The amount of chlorides at the surface is measured by a radiotracer method, using Cl36 radioisotope. The principle of the method is to detect, at the back of the electrode, the electrons which are emitted by adsorbed Cl- or Cl- incorporated in a surface film. The experimental setup allows simultaneous radiochemical and electrochemical measurements to be performed on polycrystal or single-crystal materials. Surface concentrations of chlorides in the range of the submonolayer up to chloride films can be quantitatively measured. The power of this novel method is illustrated by a study of the surface concentration of Cl- on nickel in the active and passive regions in 0.05 M H2SO4 + 5 x 10-3 M (Cl-)