POWER ABSORPTION AT METAL-SURFACES

We calculate the surface power absorption for various models of the electromagnetic fields near jellium metal surfaces, using both the d-parameter formalism and Fermi's golden rule. With Na as a test case, the absorption from an incident electromagnetic wave is examined over the frequency range between zero and twice the plasma frequency. The nature of the surface power absorption is clarified by separating it into contributions in which the excited electrons are either photoexcited into vacuum or backscattered into the bulk. We find that the total surface power absorption is well represented by the sum of these two processes, except where the bulk plasmon exists as an undamped excitation. We also show the relationship between our microscopic theory and earlier phenomenological approaches.