Orthogonal interactions of CO molecules on a one-dimensional substrate

Area of Science:

• Surface Science
• Materials Chemistry
• Nanotechnology

Background:

• Carbon monoxide (CO) typically adsorbs upright on flat metal surfaces with repulsive interactions.
• Understanding CO chemisorption on complex surfaces is crucial for catalysis and materials design.

Purpose of the Study:

• To elucidate the chemisorption structure and self-assembly of CO on a quasi-one-dimensional Cu(110)-(2 × 1)-O surface.
• To investigate the underlying mechanisms driving unusual molecular interactions and ordering.

Main Methods:

• Low-temperature scanning tunneling microscopy (LT-STM) for atomic-scale imaging.
• Density functional theory (DFT) calculations for electronic structure and bonding analysis.

Main Results:

• Single CO molecules adopt a bent chemisorption geometry (~±45°) at Cu atoms within Cu-O chains.
• At higher coverages, CO molecules form ordered, single-molecule-wide rows perpendicular to substrate chains.
• DFT reveals Cu atom lifting by ~1 Å optimizes bonding and reduces repulsion, enabling unique intermolecular interactions.

Conclusions:

• The quasi-one-dimensional Cu-O substrate induces unprecedented bent CO chemisorption and self-assembly.
• Structural distortion of the substrate is key to forming ordered molecular nanostructures.
• This study offers insights into designing novel molecular assemblies on structured surfaces.