EXAFS curve fitting results.^a

a Coordination numbers, N, interatomic distances R (Å), Debye-Waller factors σ2 (Å2), and threshold energy shift ΔE0 (eV), were derived from EXAFS curve-fitting. The fit error parameter F is defined as F=∑k6(χ(k)calc−χ(k)expt)2/∑k6χ(k)expt2, with the summation being over data points included in the fit. Values in parentheses are the estimated standard deviations obtained from the diagonal elements of the covariance matrix; these are precisions and are distinct from the accuracies which are expected to be larger (ca ± 0.02 Å for R, and ± 20% for N and σ2), although relative accuracies (e.g. comparing two different Fe—O bond-lengths) will be more similar to the precisions. EXAFS curve fitting results.a