Coherent and incoherent imaging of biological specimens with electrons and X-rays.

Peter Rez

Ultramicroscopy 2021 Dec

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Since radiation damage is proportional to fluence, radiation damage limits the spatial resolution of biological structures determined by either X-ray or electron scattering. If only elastic scattering is used for structural information then electrons are superior as the ratio of elastic to inelastic scattering is higher than for X-rays. For soft X-rays in the water window below the O K edge photoabsorption contrast might be better than elastic scattering for distinguishing different biological materials. Phase contrast elastic scattering is most effective in the hard X-ray region up to about 10 keV. Radiation damage limits spatial resolution for most X-ray imaging to 10-20 nm. Local molar concentrations of Na,K and Ca ions can be determined at somewhat lower spatial resolutions using relevant absorption edges. At higher energies resolution res is only limited by the fluence available from the light source, since energy deposition is small. Copyright © 2021 Elsevier B.V. All rights reserved.