Novel algorithms in coherent diffraction imaging using x-ray free-electron lasers

The emergence of X-ray Free-Electron Lasers has enabled coherent diffraction imaging of single nanoparticles by outrunning radiation damage with an intense ultrafast X-ray pulse. A 3D reconstruction from an ensemble of 2D diffraction patterns requires recovery of the orientations of individual diffraction patterns. This assumes that each diffraction pattern comes from a slice of a common diffraction volume. In the presence of particle heterogeneity, this assumption does not hold and the recovered structure is severely degraded. In this paper, I review couple of emerging algorithms useful for dealing with conformational changes in a heterogeneous sample. A simulated case study of a “particle in motion” is included to demonstrate the algorithms and also show that these novel algorithms work in the presence of missing Fourier regions caused by new detector geometries at XFEL facilities.