TABLE 3.

Results of a joint-fit of the eight EXAFS spectra obtained for eight distinct heating periods ranging from 0 to 180 min

Shell I	Distance vector	Coordination number/per Mn Ni	Distance/Å Ri	Debye-Waller parameter/Å2 2 σi2
I	Mn–O/N	3.92 ± 0.82* (5.5)† 3.44§	1.853 ± 0.003* 1.853§	0.0186 ± 0.0050* (0.0276)† 0.0156§
II	Mn–O	0.31 ± 0.35* (0.0) 0.06§	2.164 ± 0.002* 2.163§	0.0124 ± 0.0020* 0.0110§
		6.21‡ ± 0.40* (6.0)
III	Mn–Mn	1.02 ± 0.06* (1.0) 1.23§	2.709 ± 0.002* 2.715§	0.0046 ± 0.0020* 0.0065§
IV	Mn–Mn	0.43 ± 0.18* (0.5)	3.083 ± 0.020*	0.0027 ± 0.0025
V	Mn–Ca/Mn	0.45 ± 0.14* (0.5)	3.295 ± 0.020*	0.0027 ± 0.0025
VI	Mn–O/N/C	2.86 ± 0.55* (3.0)	3.637 ± 0.010*	0.0080 ± 0.0025

The values of R_i and σ_i of the eight spectra were coupled to yield equal numbers in all spectra (joint-fit approach); in addition the values of σ_IV and σ_V were fixed (no variation during the individual fit session). The averaged R_F value of the eight spectra was 11%. The shown N_i values refer to the intact Mn complex of PSII (no heating, 0 min) and, for shell II, also to the state resulting from 180 min of heat exposure; the resulting N_i for the other heating periods are shown in Fig. 5 (solid circles).

^*Indicated is the range of values obtained for variations in the values of σ_IV and σ_V (σ_IV = σ_V = 0.0002, 0.0027, 0.0052) and in the k-weighting (either k²- or k³-weighting for all three values of σ_IV and σ_V). This range represents the robustness of the fit with respect to variations in details of the fit approach, but not a confidence interval.

^†The values in parentheses were used for the calculation of the model spectra shown in Fig. 4.

^‡Coordination number as obtained for samples exposed to 180 min of heating.

^§Results of a three-shell simulation of the eight spectra (Fig. 5, open circles); R_i and 2σ² were coupled to yield identical values for all eight spectra; R_F was 25.0%.