Probing Copper and Copper-Gold Alloy Surfaces with Space-Quantized Oxygen Molecular Beam

Area of Science:

• Surface Science
• Chemical Physics
• Materials Science

Background:

• Molecular orientation and motion are crucial for chemical reactions.
• Dynamical steering effects in reactions complicate experimental and theoretical comparisons.
• Understanding reactant orientation is key to controlling surface reactions.

Purpose of the Study:

• To investigate the role of oxygen molecule (O2) orientation in chemisorption on copper surfaces.
• To compare O2 chemisorption on clean copper and copper-gold alloy surfaces.
• To determine the influence of gold on the reaction dynamics and anisotropy.

Main Methods:

• Utilized space-quantized molecular beams to probe O2 chemisorption.
• Investigated both polar and azimuthal orientation dependence.
• Studied O2 chemisorption on Cu(110) and Cu3Au(110) surfaces.

Main Results:

• Observed significant polar and azimuthal anisotropies in O2 chemisorption on both surfaces.
• Favorable O-O bond axis orientation was parallel to the surface and along the [001] direction.
• Gold addition increased the activation barrier and reduced azimuthal anisotropy, suppressing O2 rotation.

Conclusions:

• Molecular orientation strongly influences O2 chemisorption on copper surfaces.
• The presence of gold modifies the surface reactivity and reaction dynamics.
• Gold acts as a barrier to oxidation and restricts O2 rotational motion during chemisorption.