Outrunning damage: Electrons vs X-rays-timescales and mechanisms

    Research output: Contribution to journalArticle

    7 Citations (Scopus)

    Abstract

    Toward the end of his career, Zewail developed strong interest in fast electron spectroscopy and imaging, a field to which he made important contributions toward his aim of making molecular movies free of radiation damage. We therefore compare here the atomistic mechanisms leading to destruction of protein samples in diffract-and-destroy experiments for the cases of high-energy electron beam irradiation and X-ray laser pulses. The damage processes and their time-scales are compared and relevant elastic, inelastic, and photoelectron cross sections are given. Inelastic mean-free paths for ejected electrons at very low energies in insulators are compared with the bioparticle size. The dose rate and structural damage rate for electrons are found to be much lower, allowing longer pulses, reduced beam current, and Coulomb interactions for the formation of smaller probes. High-angle electron scattering from the nucleus, which has no parallel in the X-ray case, tracks the slowly moving nuclei during the explosion, just as the gain of the XFEL (X-ray free-electron laser) has no parallel in the electron case. Despite reduced damage and much larger elastic scattering cross sections in the electron case, leading to not dissimilar elastic scattering rates (when account is taken of the greatly increased incident XFEL fluence), progress for single-particle electron diffraction is seen to depend on the effort to reduce emittance growth due to Coulomb interactions, and so allow formation of intense sub-micron beams no larger than a virus.

    Original languageEnglish (US)
    Article number044027
    JournalStructural Dynamics
    Volume4
    Issue number4
    DOIs
    StatePublished - Jul 1 2017

    Fingerprint

    X ray lasers
    damage
    X rays
    Elastic scattering
    Electrons
    Free electron lasers
    Coulomb interactions
    free electron lasers
    elastic scattering
    electrons
    x rays
    nuclei
    Electron scattering
    Electron spectroscopy
    Radiation damage
    viruses
    Photoelectrons
    pulses
    emittance
    beam currents

    ASJC Scopus subject areas

    • Radiation
    • Instrumentation
    • Condensed Matter Physics
    • Spectroscopy

    Cite this

    Outrunning damage : Electrons vs X-rays-timescales and mechanisms. / Spence, John.

    In: Structural Dynamics, Vol. 4, No. 4, 044027, 01.07.2017.

    Research output: Contribution to journalArticle

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