XANES determination of chromium oxidation states in glasses: comparison with optical absorption spectroscopy

TL;DR

This study compares XANES and optical absorption spectroscopy for determining chromium oxidation states in glasses, finding good agreement and highlighting differences in sensitivity to chemical environment.

Contribution

It demonstrates the consistency between XANES and optical absorption methods and assesses the molar extinction coefficient of Cr(VI) in glasses.

Findings

Good agreement between XANES and optical absorption in Cr oxidation states

XANES less affected by chemical environment than optical absorption

Indirect estimation of Cr(VI) molar extinction coefficient

Abstract

The oxidation state of chromium in glasses melted in an air atmosphere with and without refining agents was investigated by Cr K-edge X-ray Absorption Near-Edge Structure (XANES) and optical absorption spectroscopy. A good agreement in the relative proportion of Cr(III) and Cr(VI) is obtained between both methods. We show that the chemical dependence of the absorption coefficient of Cr(III) is less important in XANES than in optical absorption spectroscopy. The comparison of glasses melted under different conditions provides an indirect assessment of the molar extinction coefficient of Cr(VI) in glasses.