Fig. 2. X-ray PDF analysis of the samples. LuGoe data could not be used because two phases were present, the sample and an in-line calibration standard (Fig. S2, peaks in fit residual). The grey lines at 1.936 and 2.068 Å indicate Fe–O and Fe–OH bonds of goethite, respectively, and gray bars at 3.019 and 3.412 Å correspond to Fe–Fe distances. The peak at 3.743 Å is a second coordination shell Fe–O distance. Differential patterns, [dG(r)], are calculated in real space by subtracting the undoped goethite G(r) from the doped goethite samples. The analytical error is within the width of the traces.
