Table 2. Copper EXAFS fitting results.
| Backscatterer | Coordination numbers NDFT | Coordination numbers NEXAFS | Distance RDFT (Å) | Distance REXAFS (Å) | Debye–Waller factor† Δσ2 (Å2) |
|---|---|---|---|---|---|
| Cu–OEF | 2 | 2.2 (±0.8) | 1.80 | 1.91 (±0.03) | 0.003 (±0.003) |
| Cu–OF | 1.66 | 1.6 (±0.5) | 2.02 | 2.04 (±0.07) | 0.004 (±0.005) |
| Cu–OF | 0.33 | 0.4 (±0.5) | 2.63 | 2.35 (±0.05) | 0.003 (±0.010) |
| Cu–Cu | 0.66 | 0.7 (±0.4) | 2.74 | 2.86 (±0.04) | 0.005 (±0.005) |
| Cu–Cu | 1.33 | 1.5 (±0.7) | 3.04 | 3.02 (±0.05) | 0.010 (±0.006) |
| Cu–OEF | 1 | 1.3 (±1.1) | 3.23 | 3.50 (±0.09) | 0.008 (±0.025) |
EXAFS, Extended X-ray Absoprtion Fine Structure; DFT, density functional theory; MOR, mordenite.
Comparison of Cu K-edge EXAFS fit results* for O2-activated Cu-MOR zeolite with DFT-optimized geometric parameters of [Cu3(μ-O)3]2+ in Cu-MOR.
*Combined k1, k2 and k3-weighted fit, 2.4<k<12.0 Å, 1<R<3.6, E0=−1 (3), R-factor=0.003, S02 (fixed)=0.9, statistical errors in brackets.
†Debye–Waller factors were fixed (to the values obtained in the best fit with set coordination numbers) during EXAFS fit to reduce the number of fitting parameters. The values predicted by DFT calculations are averaged over three Cu scatterers. See also Supplementary Tables 2–5.