Determination of Optical Constants of Ceria By Combined Analytical and Experimental Approaches

Abstract

Optical constants of ceria are determined in the visible and near-infrared spectral ranges. Two techniques are employed to obtain the index of refraction. The first technique is a direct procedure which involves analysis of wave interference in the transmission spectrum of a ceria thin film. The second technique is an indirect procedure that involves analysis of transmission and reflection spectrum of ceria with sintered morphology. The index of absorption is obtained in the spectral range of weak absorption using the indirect procedure. The identified index of absorption is in turn used in an alternative approach based on the subtractive Kramers–Krönig relation to estimate the spectral dependence of the index of refraction. The index of refraction identified from the measured transmittance of the thin film is qualitatively consistent with that found in the literature. The subtractive Kramers–Krönig analysis indicates that the spectral dependence of the index of refraction in the transparency range is highly sensitive to the absorption spectrum in the neighboring spectral range of strong absorption, and it is insensitive to the absorption spectrum in the spectral range of weak absorption.

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