State-to-State Spin-Orbit Changing Collision Dynamics of Vibrationally Excited NO at Collision Energies from 1.4 eV to the Cold Regime.

Abstract

State-to-state spin-orbit changing collisions of vibrationally excited nitric oxide (NO) with argon (Ar) were studied across a wide collision energy range from 3.5 to 11,200 cm^-1 (0.43 meV to 1.4 eV) using two molecular beam geometries. Stimulated emission pumping (SEP) for precise initial state preparation and velocity map imaging (VMI) for detailed scattering image capture were employed. These methods enable the study of quantum-state-resolved differential cross sections (DCSs) and provide comprehensive insight into the collision dynamics over both quantum and classical regimes. Theoretical predictions using quantum mechanical close-coupling (QMCC) calculations based on high-level coupled cluster (CCSD(T)) and multireference configuration interaction (MRCI) potential energy surfaces (PESs) are compared with experimental results enabling the testing of both repulsive and attractive parts of the PESs. This study highlights the challenges in accurately modeling spin-orbit changing collisions and underscores the importance of precise experimental data for validating theoretical models, thereby advancing our understanding of nonadiabatic collision dynamics.