Correlations in rotational energy transfer for NO-D₂ inelastic collisions

Area of Science:

• Chemical Physics
• Molecular Collisions
• Quantum Dynamics

Background:

• State-to-state inelastic collisions are fundamental to understanding chemical reactions and energy transfer processes.
• Nitrogen monoxide (NO) and deuterium (D2) are key molecules for studying fundamental collision dynamics.

Purpose of the Study:

• To experimentally and theoretically investigate state-resolved inelastic collisions between NO and D2.
• To elucidate the mechanisms of energy transfer, including spin-orbit and rotational transitions.
• To understand the role of intermolecular interactions in collision outcomes.

Main Methods:

• Utilized Stark deceleration and velocity map imaging for high-resolution collision experiments.
• Performed quantum coupled-channels calculations using advanced NO-D2 potential energy surfaces.
• Analyzed pair-correlated scattering events to resolve specific state transitions.

Main Results:

• Measured both spin-orbit conserving and changing transitions in NO.
• Observed rotational excitation and de-excitation in D2, with D2 de-excitation dependent on NO spin-orbit state.
• Identified translation-to-rotation and rotation-to-rotation energy transfer mechanisms.
• Experimental results showed excellent agreement with theoretical calculations.

Conclusions:

• The NO-D2 quadrupole-quadrupole interaction governs the observed scattering cross-section trends.
• Collision dynamics are sensitive to the initial spin-orbit state of NO and the rotational state of D2.
• The study provides a detailed understanding of energy transfer in molecular collisions.