Polaron effects on electronic properties of metal/medium interfaces: Part 2. - Electrified interfaces: In situ second harmonic generation

The linear and non-linear response of a charged metal dielectric interface to an electromagnetic field is considered within the jellium dielectric model as developed in the preceding paper. The response to the electromagnetic field is considered for two realistic field frequencies: (i) the frequency is lower than the typical frequencies of the medium and the metal, (ii) the frequency lies in the optical transparency band of the dielectric. The linear response is calculated in terms of the location of the image plane and the non-linear response in terms of the Rudnick-Stern parameter which determines the isotropic part of the second harmonic generation signal. Significantly it is found that increased screening by the slow, dipolar modes of the dielectric cause the magnitude of the Rudnick-Stern parameter to increase, while an increase in the screening by the fast, electronic modes causes the magnitude of the Rudnick-Stern parameter to decrease.