CO-NO and CO-O(2) interactions on Cu(100) between 25 and 200 K studied with infrared reflection absorption...

Area of Science:

• Surface science
• Physical chemistry
• Spectroscopy

Background:

• Understanding molecule-surface interactions is crucial for catalysis and materials science.
• Copper surfaces are important in various catalytic processes.
• Carbon monoxide (CO), nitric oxide (NO), and oxygen (O2) are key molecules in surface chemistry.

Purpose of the Study:

• To investigate the interactions between CO and NO, and CO and O2 on a Cu(100) surface.
• To analyze the effects of these interactions on the vibrational properties of CO using IRAS.
• To understand how temperature influences these surface interactions and CO adsorption geometry.

Main Methods:

• Infrared Reflection Absorption Spectroscopy (IRAS) was employed.
• Experiments were conducted on a Cu(100) single crystal surface.
• Measurements were performed at temperatures ranging from 25 K to 200 K.

Main Results:

• CO-NO coadsorption at 25 K resulted in repulsive interactions, tilting CO molecules and causing a blue-shift in vibrational frequency.
• Upon NO decomposition, CO molecules returned to a surface-normal position, with a further blue-shift to 2136 cm(-1).
• CO-O2 interaction at 27 K induced a red-shift in CO vibrational frequency, while atomic oxygen at 95 K caused a blue-shift to 2116 cm(-1), which shifted to 2091 cm(-1) upon annealing to 140 K.

Conclusions:

• The interaction dynamics between CO and coadsorbed species (NO, O2, O, N) on Cu(100) significantly alter CO adsorption geometry and vibrational frequencies.
• Temperature plays a critical role in mediating these interactions, influencing molecular tilting, decomposition pathways, and final adsorption states.
• IRAS is a powerful tool for probing subtle changes in surface molecular interactions and adsorption configurations on metal surfaces.