Electrons and X-rays for diffraction and imaging.

Area of Science:

• * Structural biology and materials science.
• * Microscopy and diffraction techniques.

Background:

• * Understanding the properties of electrons is crucial for researchers accustomed to X-ray imaging and diffraction.
• * Radiation damage, dose efficiency, and scattering mechanisms are key factors in imaging and diffraction.

Purpose of the Study:

• * To compare the utility of electrons and X-rays for collecting diffraction data from small protein crystals and imaging data from cells and tissues.
• * To analyze radiation-damage mechanisms, dose efficiency, and scattering cross-sections for both electrons and X-rays.
• * To determine crossover points where electrons and X-rays yield equivalent data quality.

Main Methods:

• * Calculation of crossover points for diffraction data quality under radiation damage.
• * Analysis of energy-dependent scattering cross-sections and contrast mechanisms.
• * Investigation of inelastic scattering effects on electron imaging and diffraction.

Main Results:

• * Increasing electron energy to 1000 keV enhances the electron/X-ray crossover point by ~43%.
• * Maximum information coefficient for electrons is achieved with 250 nm crystals at ~800 keV.
• * X-rays can locate targets (e.g., 30 nm protein) with a lower dose than tolerable for electron imaging.

Conclusions:

• * Electron microscopy and diffraction offer advantages for high-resolution imaging of small samples, especially when optimizing electron energy.
• * A hybrid approach using X-rays for initial localization followed by electron imaging can minimize dose-induced structural damage.
• * Findings are applicable to imaging across various length scales while mitigating radiation damage.