Nanocrystal Imaging Via X-ray Lasers

The ultrashort and intense light bursts generated by X-ray lasers can outpace the crystal damage they cause, thereby enabling these newly developed light sources to provide atomic structure data for a host of materials that are currently inaccessible to benchtop and synchrotron-based X-ray-analysis methods (ACS Nano,10.1021/nn1020693). That’s the conclusion of Nicusor Timneanu of Uppsala University and coworkers in Germany and Sweden, who used theoretical methods to analyze the extent of X-ray-induced lattice damage caused by Auger electron and photoelectron emission and other ionizing processes in a model system—nanocrystalline urea. The timescale on which radiation damage occurs, together with other factors, including X-ray intensity, pulse duration, and crystal size, dictates whether a sample’s atomic structure can be deduced via X-ray methods. Some proteins, for example, form submicrometer-sized crystals, which are too small for conventional X-ray analysis. The theoretical study, which addresses these factors and others, concludes that newly available X-ray lasers, such as the one at the SLAC National Accelerator Laboratory, in Menlo Park, Calif., and ones being built in Europe and Japan, will enable atomic-scale imaging of nanoscale clusters and particles and may eventually enable imaging of single biomolecules.