view article
Figure 2
Focal series of platinum–iridium (PtIr) nanocrystals on carbon. (a) Orthogonal views of a stack of 2D power spectra of micrographs, showing bright peaks associated with the PtIr reflections and the oscillations of the contrast transfer function in the background from scattering by the carbon film. (b) Orthogonal views of the 3D power spectrum of the same stack of micrographs, with the coherent spheres resulting from the focus gradient evident in the lateral views. (c) Enlarged view of the xz transverse section through the 2D power spectra showing oscillations in the intensity of the 2.25 Å reflection (red rectangle) across the focal series with a period of 627 Å (close to the focal range of 608 Å). (d) Enlarged view of the xz section through the 3D power spectrum with reflections indicated at 2.25 Å (red rectangle) and 1.39 Å (blue rectangle), each modeled as dual sinc functions.

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