Calculation of surface electromagnetic fields in laser-metal surface interaction

The semi-classical infinite barrier (SCIB) model for the calculation of surface electromagnetic fields in jellium models for metals is extended to handle smooth interfaces. In the extended model, the phenomenological nonlocal susceptibility of a semi-infinite free-electron gas is equal to the product of the nonlocal bulk susceptibility and the Fourier transform of the derivative of the normalized electron density profile. For a step function electron density profile the extended model reduces to the SCIB model, while for diffuse electron density profiles it predicts stronger surface electromagnetic fields and single-electron absorption than the SCIB model, in qualitative accord with fully numerical microscopic models. Numerical results pertinent to laser-metal surface interactions are presented for infrared, visible, and ultraviolet laser wavelengths. (C) 2001 Elsevier Science B.V. All rights reserved.