Abstract

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Imaging macromolecules using X-ray free-electron lasers

I-37

Imaging macromolecules using X-ray free-electron lasers


Henry Chapman1,2,3

1Center for Free-Electron Laser Science, DESY, Notkestrasse 85, 22607, Hamburg, Germany

2Department of Physics, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany

3The Hamburg Center for Ultrafast Imaging, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany

The short wavelength of X-rays allows us to resolve atoms, but in practise the achievable resolution is limited by the destruction of the sample by the radiation that forms the image.  For over 100 years, the workaround to this problem of radiation damage has been to average signals from repeating copies of the object arranged in a large crystal.  As first suggested by Solem and Chapline in the 1980’s, and Hajdu in 2000, the achievable resolution of images of single biological objects could be improved by using intense X-ray pulses that vaporise the sample, but which are short enough in duration to freeze the blurring of the sample.  With the advent of X-ray FELs we have been able to confirm this principle, and are now applying it to overcoming a major bottleneck for protein crystallography, which is the need for large well-diffracting crystals.  The intense pulses also open up opportunities to help solve the crystallographic phase problem.  The work suggests the feasibility of obtaining structures from much smaller samples, all the way down to the single molecule.