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Figure 10
Reconstruction of a PtIr focal series. (a) Power spectrum of a parabolic reconstruction. (b) Power spectrum of an iteratively refined parabolic reconstruction (1000 iterations). (c) Root-mean-square deviation of amplitudes of the iterative reconstruction refinement compared with the original intensities. (d) Fourier ring correlation (FRC) between the parabolic reconstruction and the refined reconstruction after 4 (green), 60 (red) and 1000 (blue) iterations. The iterative refinement recovers amplitudes at low frequencies (<1/4 Å), but introduces artifacts where the spheres intersect the Nyquist frequency in the 3D context indicated by the rings in (b) and the minima in (d). (e) FRC as in (d) for reconstructions (60 iterations) from a focal range of 640 Å (red) or 320 Å (blue), indicating the difference at frequencies below the points where the Ewald spheres separate at (640 Å × 0.025 Å)1/2 = 4 Å (red dot) and (320 Å × 0.025 Å)1/2 = 2.8 Å (blue dot), respectively.

IUCrJ
Volume 13| Part 1| January 2026| Pages 77-93
ISSN: 2052-2525
https://doi.org/10.1107/S2052252525010796