Resonance and composition effects on the Raman scattering from silver-goldalloy clusters

Low-frequency Raman scattering experiments have. been performed on thin fil ms consisting of pure gold or gold-silver alloy clusters embedded in alumin a matrix. It is clearly shown that the quadrupolar vibrational modes are ob served by Raman scattering because of the effect of resonance with the exci tation of the electronic surface dipolar plasmon. This is due to the strong coupling between the collective electronic dipolar excitation and the quad rupolar vibrational modes. This effect of resonance does not exist with the core electron excitations. The mixing of the conduction electron dipolar e xcitation (surface plasmon) with the core electrons leads to the quenching of the resonant Raman scattering.