Abstract
The spatial resolution of x-ray free-electron laser (XFEL) coherent diffraction imaging is currently limited by the fluence of XFELs. Here, we clarify this issue by systematically studying the diffraction with a SPring-8 angstrom compact free electron laser XFEL on gold nanoparticles of size from 10 nm to 80 nm in water solution. The coherent x-ray diffraction patterns obtained from single XFEL pulses were quantitatively analyzed using a small-angle x-ray scattering scheme along with computer simulations. The results show that the detectability of Au nanoparticles can be described by a “master curve” as a function of total electron density, particle size, and x-ray fluence. The difficulty in detecting a small particle under the current XFEL fluence, however, could be largely eliminated by the image enhancement effect through interference from a strong scattering nanoparticle nearby. We investigate this image enhancement effect by quantitatively analyzing the two-particle scattering from Au nanoparticles, and further, applying it to detect a weak biological object of influenza virus with the aid of an Au nanoparticle.
Highlights
In the wake of the inauguration of the first two x-ray freeelectron laser (XFEL) facilities, the Linac Coherent Light Source (LCLS) at SLAC in 20091 and the SPring-8 Angstrom Compact free electron laser (SACLA) at SPring-8 in 2012,2 intense interests have emerged to explore the structure and dynamics of both material and biological systems with the employment of unprecedented brilliant femtosecond x-ray pulses
The difficulty in detecting a small particle under the current x-ray free-electron laser (XFEL) fluence, could be largely eliminated by the image enhancement effect through interference from a strong scattering nanoparticle nearby. We investigate this image enhancement effect by quantitatively analyzing the two-particle scattering from Au nanoparticles, and further, applying it to detect a weak biological object of influenza virus with the aid of an Au nanoparticle
We systematically investigate the intensity issues of coherent x-ray diffraction (CXD) by performing in-solution oneparticle scattering of Au nanoparticles (AuNPs) of sizes ranging from a few nanometers up to ∼80 nm, recovering the missing central intensities by iterative phase-retrieval technique, and analyzing them with the framework of conventional small-angle x-ray scattering (SAXS) with validation by computer simulations
Summary
In the wake of the inauguration of the first two x-ray freeelectron laser (XFEL) facilities, the Linac Coherent Light Source (LCLS) at SLAC in 20091 and the SPring-8 Angstrom Compact free electron laser (SACLA) at SPring-8 in 2012,2 intense interests have emerged to explore the structure and dynamics of both material and biological systems with the employment of unprecedented brilliant femtosecond x-ray pulses. By plotting the scattering intensity at zero momentum transfer extrapolated from the experimental data of AuNPs of different sizes, a master curve was established This curve compares well with the ideal one calculated from AuNPs of known electron densities and where the curve vanishes defines the particle detectability, explaining that the current XFEL fluence at SACLA (1012 μm−2) and those at all other facilities with similar fluence, is insufficient to allow the detection of
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