An in Situ Study of Reconstructed Gold Electrode Surfaces by Second Harmonic Generation

Second harmonic generation (SHG) was employed to monitor in situ the potential-induced reconstruction of Au( 111) and Au( 100) electrodes. Rotating the sample by 360” about the surface normal yields for the unreconstructed Au( 1 I1 )-( 1 x 1) SWface the well-known threefold symmetry pattern in the SHG intensity, while Au( lOO)(1 X 1) shows no rotational anisotropy, as expected for C, symmetry. For the reconstructed Au( 1 I I )( 1 X 23) surface, however, an additional onefold symmetry pattern is observed, which allows in situ monitoring of the structural transition between ( I X 1) and (1 X23). For the reconstructed Au( lOO)-( 5x20) surface, a threefold symmetry pattern was found.