Determination of the anisotropy of the optical constants of electrochemically formed platinum oxide films by reflection spectroscopy and Kramers-Kronig analysis

Abstract

Reflection spectroscopy in connection with Kramers-Kronig analysis was used to evaluate the complex optical constants of a thin anisotropic film of assumed uniaxial symmetry. The change in reflectivity of a platinum electrode, due to the formation of an oxide layer, was measured between 0.9 eV and 5.2 eV for parallel and perpendicular polarization. The corresponding phase-shifts were calculated from these data. The complex optical constants normal n̂ n and tangential n̂ t to the surface are now obtainable. The spectral dependence of the complex optical constants shows the expected anisotropic behaviour. The results are explained by means of a simple band model.