Optical scattering from oxidized metals. 1: Model formulation and properties.

Strong scattering, which exhibits a conspicuous wavelength dependence, has been experimentally observed from certain oxidized metals. A model is presented which combines the effects of interface illumination in a new normalization procedure with the scalar scattering reduction of the Fresnel interface reflectance coefficients. The model is used to calculate the specular and the diffuse part of the hemispheric reflectance from the double layer, with oxide thickness and rms roughness as input parameters. The results give a qualitatively correct spectral variation and underline the importance of the substrate reflectance. The results also illustrate an interesting difference in scattering behavior, whether the front surface or the oxide-metal interface is rough.