ON THE ORIGIN OF SURFACE 2ND-HARMONIC ANISOTROPY ON AG(111) AT LOW-FREQUENCIES

It is shown that the magnitude of the surface rotational SHG anisotrop y on Ag(111) in the low-frequency limit is related to features of the silver band structure in the vicinity of the Fermi level rather than t o electron transitions involving the filled d-states or surface states . The band structure near E(F) is, however, affected by hybridization with the d-stares and, therefore, the d-electrons affect the anisotrop y indirectly. The spatial extent of the anisotropic nonlinear current and its sensitivity to surface properties are discussed.