Experimental strategies for imaging bioparticles with femtosecond hard X-ray pulses
Category
Published on
Type
journal-article
Author
Benedikt J. Daurer and Kenta Okamoto and Johan Bielecki and Filipe R. N. C. Maia and Kerstin Mühlig and M. Marvin Seibert and Max F. Hantke and Carl Nettelblad and W. Henry Benner and Martin Svenda and Nicuşor Tîmneanu and Tomas Ekeberg and N. Duane Loh and Alberto Pietrini and Alessandro Zani and Asawari D. Rath and Daniel Westphal and Richard A. Kirian and Salah Awel and Max O. Wiedorn and Gijs van der Schot and Gunilla H. Carlsson and Dirk Hasse and Jonas A. Sellberg and Anton Barty and Jakob Andreasson and Sébastien Boutet and Garth Williams and Jason Koglin and Inger Andersson and Janos Hajdu and Daniel S. D. Larsson
Citation
Daurer, B.J. et al., 2017. Experimental strategies for imaging bioparticles with femtosecond hard X-ray pulses. IUCrJ, 4(3). Available at: http://dx.doi.org/10.1107/s2052252517003591.
Abstract
This study explores the capabilities of the Coherent X-ray Imaging Instrument at the Linac Coherent Light Source to image small biological samples. The weak signal from small samples puts a significant demand on the experiment. AerosolizedOmono River virusparticles of ∼40 nm in diameter were injected into the submicrometre X-ray focus at a reduced pressure. Diffraction patterns were recorded on two area detectors. The statistical nature of the measurements from many individual particles provided information about the intensity profile of the X-ray beam, phase variations in the wavefront and the size distribution of the injected particles. The results point to a wider than expected size distribution (from ∼35 to ∼300 nm in diameter). This is likely to be owing to nonvolatile contaminants from larger droplets during aerosolization and droplet evaporation. The results suggest that the concentration of nonvolatile contaminants and the ratio between the volumes of the initial droplet and the sample particles is critical in such studies. The maximum beam intensity in the focus was found to be 1.9 × 1012photons per µm2per pulse. The full-width of the focus at half-maximum was estimated to be 500 nm (assuming 20% beamline transmission), and this width is larger than expected. Under these conditions, the diffraction signal from a sample-sized particle remained above the average background to a resolution of 4.25 nm. The results suggest that reducing the size of the initial droplets during aerosolization is necessary to bring small particles into the scope of detailed structural studies with X-ray lasers.
