Optical properties of adsorbate atoms

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Abstract
We calculate the dielectric response of adsorbate atoms on a metal surface assuming an Anderson model of the system. The dielectric function is then used to predict the change in the surface optical reflectance caused by the adsorbates. General results are obtained for substrates with one and two electron bands with and without the assumption of momentum conservation in the band-to-band optical transitions. A detailed analysis is carried out for the single-band momentum-conserving case. Here, the model is the same as that studied by Caroli and Kjollerstrom if the substrate density of states and various matrix elements are taken to be constants. However, we find an additional nonnegligible contribution omitted in their analysis. In other single-band cases, we show the wide variety of behavior which may be obtained for different parameter ranges and provide expressions to be used in data analyses.