Second harmonic generation by cold-deposited silver films

The second harmonic generation (SHG) of light diffusely scattered by cold-deposited silver films is negligible with respect to the specular intensities. Therefore, a cold-deposited silver him is well approximated by a homogeneous effective medium. The intensities of SHG at 1.06 mu m and the optical absorption at 0.53 mu m depend on both the square of the internal effective field at 0.53 mu m and a change in the same way when annealing the film. This can be understood by the assumption that SHG is also mainly following the electric field within the metal phase and surface contributions to SHG interfere destructively. This is corroborated by the observation that the SHG intensity does not show the 'chemical first layer effects' seen by surface-enhanced Raman scattering (SERS). (C) 1999 Elsevier Science B.V. All rights reserved.