Rotational Anisotropy in the Second Harmonic Response from Cu(111) in AqueousSolution

摘要

Rotational anisotropy in the second harmonic response has been measured for aCu(111) electrode in solution. A 3-fold symmetric pattern is observed for the p-polarized response which does not change in form or in magnitude as a function of bias potential. These results are compared with similar studies of Ag(111) electrodes in solution and studies of Cu(111) surfaces in ultrahigh vacuum and under ambient conditions. In addition, the effect of surface modification by the underpotential deposition of thallium overlayers on the nonlinear optical response of the Cu(111) electrode has been measured. The isotropic contribution to the second harmonic response is shown to be sensitive to the details of the overlayer formation, whereas the anisotropic contribution does not change.