Weak intermolecular interactions in an ionically bound molecular adsorbate: cyclopentadienyl/Cu(111)

Area of Science:

• Surface Science
• Physical Chemistry
• Computational Chemistry

Background:

• Understanding molecule-surface interactions is crucial in catalysis and materials science.
• Cyclopentadiene adsorption on metal surfaces is a key step in various chemical processes.

Purpose of the Study:

• To investigate the dissociative adsorption of cyclopentadiene on Cu(111).
• To determine the potential energy surface and frictional coupling of the resulting cyclopentadienyl species.
• To characterize the molecular motion and interactions on the copper surface.

Main Methods:

• Experimental measurements of molecular dynamics.
• Density functional theory (DFT) calculations.
• Analysis of adsorption sites and energy barriers.

Main Results:

• Formation of a strongly anionic cyclopentadienyl (Cp) species.
• Identification of degenerate threefold adsorption sites.
• Characterization of molecular motion with a low diffusional energy barrier (40±3 meV) and strong frictional dissipation.
• Absence of detected repulsive dipole-dipole interactions despite charge transfer.

Conclusions:

• The adsorption of cyclopentadiene on Cu(111) leads to a highly anionic Cp species.
• Molecular dynamics are governed by low diffusion barriers and significant friction.
• The study provides insights into charge transfer and intermolecular interactions at the molecule-surface interface.