A STUDY OF THE UNDERPOTENTIAL DEPOSITION OF LEAD ON GOLD BY UV-VISIBLE DIFFERENTIAL REFLECTANCE SPECTROSCOPY

The underpotential deposition of lead on gold has been studied by cycl ic voltammetry and UV-visible differential reflectance spectroscopy. C omparative experiments were carried out with a polycrystalline gold el ectrode and two single-crystal gold electrodes with the orientations ( 111) and (210). For the single crystal surfaces, the reflectance resul ts confirm the large effect of the crystallographic orientation on the deposition and redissolution of lead on gold surfaces. The existence of different types of structures for adsorbed lead, depending not only on the atomic distribution of the substrate but above all on the elec trode potential, is demonstrated. An attempt is made to explain the be havior of polycrystalline gold on the basis of the results obtained fo r the two investigated gold single crystal faces.