A method for realizing sub-angstrom spatial resolution in diffractive imaging of single nanocrystals

Diffractive imaging is a technique for so-called lens-less microscopy, and uses diffraction intensity (image) and phase retrieval calculations rather than focusing systems such as lenses, which are not free from aberrations. The spatial resolution is basically limited only by the amount of high-angle scattering. Therefore, the technique has been considered as having the potential to achieve atomic resolution for hard X-rays or other short-wavelength particle beams. However, so far, the reported results have been still at the level of several nanometers. Recently, a research group at the University of Illinois, USA proposed a method of improving the resolution. One of the biggest technical reasons limiting the spatial resolution of diffractive imaging is the difficulty of recording weak coherent scattering signals. The research group proposes the combined use of low-resolution imaging, which provides the starting phase, real-space constraint, missing information in the central beam and essential marks for aligning the diffraction pattern. The group used an electron microscope to see a single CdS quantum dot with sub-angstrom resolution and noted that it is possible to use the same procedure in the case of coherent X-ray scattering. For more information, see the paper, "Sub-angstrom-resolution diffractive imaging of single nanocrystals", W. J. Huang et al., Nature Physics, advanced online publication doi:10.1038/nphys1161