Second harmonic generation study of the reconstruction of an Au(110) electrode in HClO4

Second harmonic generation (SHG) was used to carry out an in situ study of the potential-induced reconstruction of an Au(110) single crystal electrode in an aqueous solution of 0.01 M HClO4. In this study, we found that the symmetries of the surface susceptibility of the reconstructed and the unreconstructed Au(110) surfaces have a large component of threefold symmetry. A detailed analysis shows that both surfaces have an overall C-s symmetry giving one-, two-, and threefold symmetries for the surface susceptibility. However, another, different, source of threefold symmetry, perpendicular to the first, is needed to fit the data. We suggest that this extra source of threefold symmetry is due to the (111) microfacets that are present on the open (110) surface.