High-fluence and high-gain multilayer focusing optics to enhance spatial resolution in femtosecond X-ray laser imaging.

Yumoto, Hirokatsu; Koyama, Takahisa; Suzuki, Akihiro; Joti, Yasumasa; Niida, Yoshiya; Tono, Kensuke; Bessho, Yoshitaka; Yabashi, Makina et al. · Nat Commun · 2022

basic_science · Level V

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Abstract

With the emergence of X-ray free-electron lasers (XFELs), coherent diffractive imaging (CDI) has acquired a capability for single-particle imaging (SPI) of non-crystalline objects under non-cryogenic conditions. However, the single-shot spatial resolution is limited to ~5 nanometres primarily because of insufficient fluence. Here, we present a CDI technique whereby high resolution is achieved with very-high-fluence X-ray focusing using multilayer mirrors with nanometre precision. The optics can focus 4-keV XFEL down to 60 nm × 110 nm and realize a fluence of >3 × 10<sup>5</sup> J cm<sup>-2</sup> pulse<sup>-1</sup> or >4 × 10<sup>12</sup> photons μm<sup>-2</sup> pulse<sup>-1</sup> with a tenfold increase in the total gain compared to conventional optics due to the high demagnification. Further, the imaging of fixed-target metallic nanoparticles in solution attained an unprecedented 2-nm resolution in single-XFEL-pulse exposure. These findings can further expand the capabilities of SPI to explore the relationships between dynamic structures and functions of native biomolecular complexes.