Full-dimensional quantum dynamics of CO in collision with H2

Area of Science:

• Physical Chemistry
• Chemical Physics
• Quantum Mechanics

Background:

• Understanding energy transfer in molecular collisions is crucial for various chemical processes.
• Carbon monoxide (CO) and hydrogen (H2) are fundamental molecules in astrochemistry and combustion.
• Accurate theoretical models are needed to interpret experimental scattering data.

Purpose of the Study:

• To perform full-dimension inelastic scattering computations for CO-H2 collisions.
• To investigate rotational and vibrational energy transfer dynamics.
• To compare theoretical predictions with recent experimental measurements.

Main Methods:

• Utilized a new six-dimensional and a previous four-dimensional potential energy surface (PES).
• Incorporated full angular-momentum coupling in the scattering calculations.
• Calculated pure rotational excitation and rovibrational quenching cross sections.

Main Results:

• Achieved good agreement between computed and measured rotational excitation cross sections, with discrepancies at very low energies for para-H2.
• Rovibrational quenching cross sections showed similar magnitudes for para- and ortho-H2, with energy-dependent trends related to initial CO rotational states.
• Pure rotational deexcitation cross sections were similar for different CO vibrational levels, but rovibrational quenching from v1=2 was significantly larger than from v1=1.

Conclusions:

• The developed potential energy surfaces and computational methods accurately describe CO-H2 inelastic scattering.
• Minor differences exist between para- and ortho-H2 colliders, particularly at low collision energies.
• The study provides valuable data for understanding energy transfer in chemically relevant systems.