Abstract: Adsorption of anions on the surface of polycrystallirie copper of metal/aqueous solution interface was monitored with optical second harmonic generation (SHG). The SHGsignal is strongly affected by the anion adsorption on the surface. Excess charge density on the metal surface is concluded to be a major factor in the voltage-dependent production of the harmonic light. In this paper, the SHGintensity-voltage curves for polycfystalline copper in (0. 5 - x) mol/L NaClO⁴+x mol/L NaBr solutions for x in various values are presented. The results show that the perchlorate anion is quite weakly adsorbed at the surface and the halide ion is. a specific adsorption. The results demonstrate that the dominant feature in the voltage-dependent signal is a rise in harmonic light intensity with increasing halide ion concentration. In this case the metal-adsorbate interaction is a particularly clear manifest inthe SHG signal-voltage curves. The results of these studies show evidently that the SHG method Is aquite sensitive arid effective probe for monitoring adsorption quantitatively on the electrochemical interface.

Key words: Crystal, Copper electrode, Laser, Second harmonic generation, Adsorbed ions