Coherent diffractive imaging: towards achieving atomic resolution

Dietze, S.H.; Shpyrko, O.G.

doi:10.1107/S1600577515017336

Figure 2
Crystalline Au particle. (a) Achievable resolution at various photon statistics, where the solid line is the theoretical model described by equation (2)

and circles are reconstructions using CXDI from simulated photon statistics. The horizontal dashed line indicates the pixel size below which the current simulations cannot reach, and the dashed line which follows much of the theoretical curve indicates the expected $[\delta x^{\,{-5}}]$ fall-off for a uniform particle. To show local resolution, a subset of recovered atomic positions near a vacancy (b)–(e) and near a screw dislocation (f)–(k) are shown, where atomic position ME and MAE (a) are also given. (b) For the actual atomic position near a vacancy there is an atom missing at the center surrounded by an inward distortion of neighboring atoms within 5 Å. (c) This is fully recovered by 2 × 10¹⁸ photons µm⁻². (d) With 1.5 × 10¹⁸ photons µm⁻² the vacancy and distortion can still be identified. (e) By 10¹⁸ photons µm⁻² the vacancy is no longer present and only a slight distortion of neighboring atoms is seen. (f) For the actual atomic position near a screw dislocation, a shift of atoms by a unit cell occurs as seen from the [111] direction with characteristic width of 5 Å. (g) This is effectively recovered by 2 × 10¹⁸ photons µm⁻² within the expected resolution. (h) With 4 × 10¹⁷ photons µm⁻² the dislocation can still be recognized. (k) Finally, at 10¹⁷ photons µm⁻², only a periodic atomic structure is recovered. The dashed spheres designate the actual atomic positions for comparison.

JOURNAL OF
SYNCHROTRON
RADIATION

ISSN: 1600-5775

Volume 22| Part 6| October 2015| Pages 1498-1508

doi:10.1107/S1600577515017336

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