Table 4.
First-shell EXAFS Curve-Fitting Results for Biferrous DFsc, Biferrous DFscY51L, and Biferrous DFscE11D.a
| DFsc | DFscY51L | DFscE11D | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| fit no. | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | |
| Fe–O/Nb | N | 5 | 2 | 2 | 5 | 2 | 2 | 5 | 2 | 2 |
| R (Å) | 2.07 | 2.02 | 2.03 | 2.07 | 2.02 | 2.03 | 2.07 | 2.01 | 2.02 | |
| σ2 × 105 (Å2) | 1230 | 370 | 390 | 1040 | 470 | 530 | 1140 | 500 | 540 | |
| Fe–O/Nb | N | – | 3 | 3 | – | 3 | 3 | – | 3 | 3 |
| R (Å) | – | 2.16 | 2.16 | – | 2.14 | 2.14 | – | 2.13 | 2.14 | |
| σ2 × 105 (Å2) | – | 650 | 700 | – | 670 | 810 | – | 710 | 820 | |
| Fe–C | N | – | – | 1 | – | – | 1 | – | – | 1 |
| R (Å) | – | – | 2.55 | – | – | 2.55 | – | – | 2.54 | |
| σ2 × 105 (Å2) | – | – | 470 | – | – | 200 | – | – | 400 | |
| Fe–C | N | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 |
| R (Å) | 2.96 | 3.00 | 3.00 | 2.96 | 2.99 | 2.99 | 2.96 | 3.01 | 3.01 | |
| σ2 × 105 (Å2) | 590 | 390 | 430 | 730 | 460 | 570 | 1000 | 760 | 810 | |
| ΔE0, eV | −9.1 | −6.0 | −5.7 | −8.4 | −6.0 | −5.9 | −7.1 | −4.6 | −4.4 | |
| Fc | 0.433 | 0.393 | 0.391 | 0.345 | 0.333 | 0.309 | 0.270 | 0.255 | 0.233 | |
a
All fits were performed over the k range of 2-15 Å-1. The estimated uncertainty in R is ± 0.02 Å for the first shell and ± 0.05 Å for outer shells; the uncertainty in N is ~25%.
b
Scatterers differing by Z ± 1 are not distinguishable in an EXAFS fit. The first element in a pair indicates the type of atom used to model the backscattered wave in the FEFF calculation.
c
The goodness of the fit is defined as F = [Σ(k6(χexptl – χcalcd)2)/(Σk6χexptl2)]½.