Carbon Monoxide Hydrogenation on Ice Surfaces.

Area of Science:

• Astrochemistry
• Computational Chemistry
• Surface Science

Background:

• Carbon monoxide hydrogenation is crucial for interstellar chemistry.
• Understanding reaction kinetics on ice surfaces is vital for astrochemical models.
• Computational methods are needed to study reactions in simulated interstellar environments.

Purpose of the Study:

• Investigate the carbon monoxide hydrogenation reaction (H+CO→HCO) on amorphous and crystalline ice surfaces.
• Determine the activation energy and reaction rates for this important interstellar reaction.
• Develop a simplified method to estimate activation energies on ice surfaces.

Main Methods:

• Density functional theory (DFT) calculations were employed.
• Calculations were performed on both amorphous and crystalline ice models.
• Quantum-tunneling effects were incorporated to discuss reaction rates.

Main Results:

• The activation energy for H+CO→HCO is lower on amorphous ice than crystalline ice.
• A correlation was found between activation energy and excitation energy of CO, simplifying calculations.
• The reaction rate on amorphous ice is estimated to be nearly twice that on crystalline ice.

Conclusions:

• Amorphous ice significantly influences the kinetics of carbon monoxide hydrogenation.
• The excitation energy of CO can serve as a proxy for activation energy, easing computational demands.
• Findings align with experimental observations and improve astrochemical models.