A prominent deficiency of Z-contrast imaging is its inability to reveal light atoms neighboring heavy elements. The below Fe3O4 example shows how ptychography can better reveal such light elements in comparison to other STEM modalities, especially at lower doses where its dose efficiency outshines that of iCoM.
O columns are shown in red in the model, Fe in brown.
Overcoming Contrast Reversals in
Focused Probe Ptychography of Thick Materials: An Optimal Pipeline for
Efficiently Determining Local Atomic Structure in Materials
C. Gao, C. Hofer, D. Jannis, A. Béché, J. Verbeeck, T. J. Pennycook
Applied Physics Letters 121, 081906 (2022).