Experimental Evidence for a Three-Body Interaction between Diffusing CO Molecules.

Area of Science:

• Surface science
• Physical chemistry
• Materials science

Background:

• Understanding molecular diffusion on metal surfaces is crucial for catalysis and materials development.
• Carbon monoxide (CO) adsorption and diffusion on copper (Cu) surfaces, particularly Cu(111), are fundamental processes in surface chemistry.
• Previous studies have focused on pairwise interactions, but multi-particle interactions remain less understood.

Purpose of the Study:

• To experimentally investigate the diffusion of carbon monoxide (CO) molecules on a Cu(111) surface at low temperatures.
• To validate theoretical predictions regarding multi-particle interactions influencing adsorbate diffusion barriers.
• To explore the role of trio interactions in CO diffusion dynamics.

Main Methods:

• Utilizing time-lapsed scanning tunneling microscopy (STM) to observe CO diffusion.
• Conducting experiments within a specific low-temperature range (30–38 K).
• Analyzing distance-dependent variations in diffusion energy.

Main Results:

• Experimental evidence confirms the theoretical prediction of a 'trio interaction' affecting diffusion barriers.
• Observed diffusion energy variations are consistent with theoretical models that include beyond pairwise interactions.
• The study quantifies the impact of proximity on the diffusion behavior of CO molecules.

Conclusions:

• The findings validate the asymptotic theory of adsorbate diffusion, highlighting the significance of trio interactions.
• This research provides a foundation for more accurate theoretical modeling of surface diffusion phenomena.
• The developed theoretical framework can be extended to understand nucleation and reaction processes on surfaces.