Infrared Reflectance Kramers-Kronig Analysis by Anchor-Window Technique

An algorithm for the Kramers-Kronig analysis of the reflectivity spectra, based on an anchor-window technique is presented. The high-frequency asymptote, required for the Kramers-Kronig analysis, is determined by minimizing differences between the Kramers-Kronig-deduced optical constants of a system under investigation and known optical constants measured in a small anchor-window. The algorithm is illustrated by applying it for a reconstruction of the optical conductivity σ(ω) of the fci-ZnMgRE quasicrystals in the spectral range of 0.01-6.5 eV from the experimental IR Fourier-transform reflectivity data and the experimental spectral ellipsometry VIS-UV data. The reliability of the suggested Kramers-Kronig analysis technique is confirmed by independent infrared spectral ellipsometry σ(ω) measurements for fci-ZnMgRE.