  Identifying the three-dimensional (3D) crystal-plane and strain-field
distributions of nanocrystals is essential for optical, catalytic, and
electronic applications. Here, we developed a methodology for visualizing the
3D information of chiral gold nanoparticles with concave gap structures by
Bragg coherent X-ray diffraction imaging. The distribution of the
high-Miller-index planes constituting the concave chiral gap was precisely
determined. The highly strained region adjacent to the chiral gaps was
resolved, which was correlated to the 432-symmetric morphology of the
nanoparticles and its corresponding plasmonic properties were numerically
predicted from the atomically defined structures. This approach can serve as a
general characterization platform for visualizing the 3D crystallographic and
strain distributions of nanoparticles, especially for applications where
structural complexity and local heterogeneity are major determinants, as
exemplified in plasmonics.
