We report 3D coherent diffractive imaging (CDI) of Au/Pd core-shell nanoparticles with 6.1 nm spatial resolution with elemental specificity. We measured single-shot diffraction patterns of the nanoparticles using intense x-ray free electron laser pulses. By exploiting the curvature of the Ewald sphere and the symmetry of the nanoparticle, we reconstructed the 3D electron density of 34 core-shell structures from these diffraction patterns. To extract 3D structural information beyond the diffraction signal, we implemented a super-resolution technique by taking advantage of CDI's quantitative reconstruction capabilities. We used high-resolution model fitting to determine the Au core size and the Pd shell thickness to be 65.0 ± 1.0 nm and 4.0 ± 0.5 nm, respectively. We also identified the 3D elemental distribution inside the nanoparticles with an accuracy of 3%. To further examine the model fitting procedure, we simulated noisy diffraction patterns from a Au/Pd core-shell model and a solid Au model and confirmed the validity of the method. We anticipate this super-resolution CDI method can be generally used for quantitative 3D imaging of symmetrical nanostructures with elemental specificity.
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Pryor, Alan; Rana, Arjun; Xu, Rui; Rodriguez, Jose A; Yang, Yongsoo; Gallagher-Jones, Marcus; Jiang, Huaidong; Kanhaiya, Krishan; Nathanson, Michael; Park, Jaehyun; Kim, Sunam; Kim, Sangsoo; Nam, Daewoong; Yue, Yu; Fan, Jiadong; Sun, Zhibin; Zhang, Bosheng; Gardner, Dennis F; Dias, Carlos Sato Baraldi; Joti, Yasumasa; Hatsui, Takaki; Kameshima, Takashi; Inubushi, Yuichi; Tono, Kensuke; Lee, Jim Yang; Yabashi, Makina; Song, Changyong; Ishikawa, Tetsuya; Kapteyn, Henry C; Murnane, Margaret M; Heinz, Hendrik; and Miao, Jianwei, "Single-shot 3D coherent diffractive imaging of core-shell nanoparticles with elemental specificity." (2018). Physics Faculty Contributions. 131.