L edge chemical shift and bond length difference of the mixed oxidation Ce3+/Ce4+ redox couple in solution

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Abstract
L edge absorption spectra of the Ce3+/Ce4+ redox couple in solution have been recorded with synchrotron radiation. It is found that the L2 and L3 near edges exhibit large chemical shifts (7.3–9.0 eV) between the intense resonance (‘‘white line’’) of Ce3+ and Ce4+ ions in solution. This shift is interpreted in terms of atomic and chemical effects and is correlated with thermodynamic parameters. Analysis of the L3 edge EXAFS gives an average Ce3+–H2O distance of 2.50±0.02 Å. The lower bound of the Ce–H2O bond length difference between Ce(H2O)4+n and Ce(H2O)3+n in solution is estimated to be 0.07±0.02 Å.