Coherent diffractive imaging

Coherent diffractive imaging: Ilme Schlichting

Structural biology, and in particular scattering based techniques making use of X-rays and electrons, has provided high-resolution insight in the structure and function of molecules, molecular assemblies, and cells. Despite a lot of advances in instrumentation, radiation damage limits high resolution imaging of biological material using conventional X-ray or electron based approaches. X-ray free-electron lasers (FELs) exceed the peak brilliance of conventional synchrotrons by almost 10 billion times. They promise to break the nexus between radiation damage, sample size, and resolution by providing extremely intense femtosecond X-ray pulses that pass the sample before the onset of significant radiation damage.

<p>Experimental setup of coherent diffraction imaging of single particles, such as viruses. See Kassemeyer et al Optics Express 20: 4149-58 (2012).</p> Zoom Image

Experimental setup of coherent diffraction imaging of single particles, such as viruses. See Kassemeyer et al Optics Express 20: 4149-58 (2012).

Since the sample is destroyed by the FEL pulse, it needs to be replenished after each exposure using liquid microjets in the case of crystalline samples and aerodynamic lenses in the case of airborne single particles. The concept of “diffraction-before-destruction” has been demonstrated recently at the Linac Coherent Light Source (LCLS), the first operational hard X-ray FEL, for tiny protein crystals [1] and single mimivirus particles.[2]  The experiments were performed by a large internationional collaboration, using the CFEL ASG multi- purpose (CAMP) instrument[3]  designed and operated by the Advanced Study Group (ASG) of which we are a member. We are exploring the possibilities of serial femtosecond crystallography (SFX) and coherent diffractive imaging (CDI) using suitable model systems to study challenging ones. We are using a number of approaches that include theory, computation and instrumentation. With its biochemistry/biophysics/virology/chemistry groups, our depart­ment is perfectly equipped and positioned to develop and study interesting projects.

  1. Chapman, H. N. et al. Femtosecond X-ray protein nanocrystallography. Nature 470, 73-77 (2011)
    [Abstr] [Full] [PDF] [DOI]

  2. Seibert, M. M. et al. Single mimivirus particles intercepted and imaged with an X-ray laser. Nature 470, 78-81 (2011)
    [Abstr] [Full] [PDF] [DOI]

  3. Strüder, L. et al Large-format, high-speed, X-ray pnCCDs combined with electron and ion imaging spectrometers in a multipurpose chamber for experiments at 4th generation light sources. Nuclear Instruments and Methods in Physics Research A 614, 483-496 (2010)

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