Theoretical Study of the Photochemical Mechanisms of the Electronic Quenching of NO(A(2)Σ(+)) with CH(4), CH(3)OH, and CO(2)

[Image: see text] The electronic quenching of NO(A(2)Σ(+)) with molecular partners occurs through complex non-adiabatic dynamics that occurs on multiple coupled potential energy surfaces. Moreover, the propensity for NO(A(2)Σ(+)) electronic quenching depends heavily on the strength and nature of the intermolecular interactions between NO(A(2)Σ(+)) and the molecular partner. In this paper, we explore the electronic quenching mechanisms of three systems: NO(A(2)Σ(+)) + CH(4), NO(A(2)Σ(+)) + CH(3)OH, and NO(A(2)Σ(+)) + CO(2). Using EOM-EA-CCSD calculations, we rationalize the very low electronic quenching cross-section of NO(A(2)Σ(+)) + CH(4) as well as the outcomes observed in previous NO + CH(4) photodissociation studies. Our analysis of NO(A(2)Σ(+)) + CH(3)OH suggests that it will undergo facile electronic quenching mediated by reducing the intermolecular distance and significantly stretching the O–H bond of CH(3)OH. For NO(A(2)Σ(+)) + CO(2), intermolecular attractions lead to a series of low-energy ON–OCO conformations in which the CO(2) is significantly bent. For both the NO(A(2)Σ(+)) + CH(3)OH and NO(A(2)Σ(+)) + CO(2) systems, we see evidence of the harpoon mechanism and low-energy conical intersections between NO(A(2)Σ(+)) + M and NO(X(2)Π) + M. Overall, this work provides the first detailed theoretical study on the NO(A(2)Σ(+)) + M potential energy surface of each of these systems and will inform future velocity map imaging experiments.