Diffusion of N adatoms on the Fe(100) surface

Area of Science:

• Surface science
• Materials science
• Physical chemistry

Background:

• Understanding adatom diffusion on metal surfaces is crucial for catalysis and materials design.
• Nitrogen adatoms on iron surfaces are relevant to processes like ammonia synthesis.

Purpose of the Study:

• To investigate the diffusion mechanisms of individual nitrogen adatoms on a Fe(100) surface.
• To determine the diffusion barrier and prefactor for nitrogen adatoms.
• To explore the influence of adsorbate-adsorbate interactions and lattice distortions on diffusion.

Main Methods:

• Experimental study using scanning tunneling microscopy (STM).
• Theoretical calculations using ab initio density functional theory (DFT).
• Determination of potential energy surfaces based on experimental and theoretical data.

Main Results:

• Measured diffusion barrier for isolated N adatoms: E(d) = (0.92 ± 0.04) eV.
• Measured prefactor: ν(0) = 4.3 × 10^12 s⁻¹, in quantitative agreement with DFT.
• Diffusion is strongly coupled to lattice distortions, leading to anisotropic diffusion in the presence of other N adatoms.

Conclusions:

• The study provides a comprehensive understanding of nitrogen adatom diffusion on Fe(100).
• Experimental and DFT results quantitatively agree, validating the theoretical approach.
• Lattice distortions and adsorbate interactions significantly impact nitrogen diffusion dynamics on metal surfaces.