Molecular imaging with x-ray free-electron lasers

High resolution imaging of biological macromolecules using x-ray crystallography is a key component of modern molecular biology, the results of which are essential for understanding biological processes in health and disease, and for drug design. Macromolecular imaging is currently undergoing a revolution as a result of the recent availability of x-ray free-electron lasers (XFELs). XFELs produce extremely intense, ultra-short x-ray pulses which offer the possibility of imaging specimens that are different to the 3D crystals used in conventional x-ray crystallography. The application of XFEL imaging to nano-crystalline fibrous specimens - long, slender systems that are periodic in their axial direction exhibit partial lateral crystallinity - is investigated. It is shown that individual Fourier amplitudes can be measured from XFEL data from such specimens. It is demonstrated that the image reconstruction problem from diffraction data for specimens with reduced crystallinity, specifically 2D membranes, is achievable. Although such specimens are weakly diffracting, they potentially offer more information in their diffraction than do 3D crystals. Image reconstruction is demonstrated by simulation.