First-Principle Calculation on Inelastic Electron Scattering in Diamond and Graphite.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Surface Science

Background:

• Secondary electron emission (SEE) is crucial for understanding material properties and surface interactions.
• Significant differences in SEE yields between diamond and graphite are observed but not fully understood.
• Inelastic electron scattering plays a key role in electron emission processes.

Purpose of the Study:

• To investigate the underlying mechanisms responsible for the differing secondary electron emission yields between diamond and graphite.
• To analyze the influence of inelastic electron scattering on electron transport properties in these materials.
• To elucidate the directional dependence of electron interactions within diamond and graphite.

Main Methods:

• Utilizing first-principle calculations to determine dielectric functions and energy loss functions.
• Calculating direction-dependent energy loss functions and inelastic mean free path (IMFP).
• Simulating electron transport and secondary electron excitation depths and directions.

Main Results:

• Diamond exhibits isotropic electronic properties, while graphite shows directional dependencies.
• The IMFP of diamond is lower than that of graphite for electron energies above 30 eV.
• In graphite, incident electrons exhibit directional preferences, leading to deeper SE excitation and more horizontal electron motion.
• These directional effects in graphite explain the observed differences in secondary electron yield (SEY).

Conclusions:

• Inelastic electron scattering properties significantly differ between diamond and graphite.
• Directional electron motion in graphite leads to deeper excitation and anisotropic SEE, explaining its lower SEY compared to diamond.
• Understanding these fundamental differences is key for applications involving electron-matter interactions.