Effects of reactant rotational excitations on H2 + NH2 → H + NH3 reactivity

Photodetachment and Tunneling Dissociation of Cryogenic Double-Rydberg Anions NH4. J Phys Chem Lett 2024;15:5612-5617. [PMID: 38758204 DOI: 10.1021/acs.jpclett.4c01168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

The Rydberg radical NH4 and the double Rydberg anion (DRA) NH4- have long aroused researchers' interests due to their potential for exploring the reaction dynamics of the H + NH3 → H2 + NH2 reaction, a prototypical penta-atomic system. In this study, we present high-resolution photodetachment spectroscopy of DRA NH4- and ion-molecule complex H-(NH3). We observed multiple new photodetachment channels of DRA NH4-. The energy level of the excited state (3p 2T2) of the Rydberg radical NH4 was determined to be 15052(94) cm-1, in excellent agreement with the principal Schüler band (15061.61 cm-1). Additionally, we observed the tunneling dissociation of NH4- in a cryogenic ion trap with its dissociation lifetime determined to be 19(2) ms.

Toward a Comprehensive Understanding of Mode-Specific Dynamics of Polyatomic Reactions: A Full-Dimensional Quantum Dynamics Study of the H + NH3 Reaction

Mode specificity not only sheds light on reaction dynamics but also opens the door for chemical reaction control. This work reports a state-of-the-art full-dimensional quantum dynamics study on the prototypical hydrogen abstraction reaction of hydrogen with ammonia, which serves as a benchmark for advancing our fundamental understanding of polyatomic reaction dynamics. By taking advantage of the (3 + 1) Radau-Jacobi coordinates, the bond-specific probabilities are resolved with the reactant NH₃ initiated from either a non-degenerate or degenerate stretching vibrational state. The observed different atom-specific abstraction probabilities from individual states of the degenerate pair are rationalized in the local mode representation according to the different vibrational energy deposited in each N-H bond. It is verified that the three H atoms in NH₃ have the same abstraction probability as that from the degenerate pair and the linear combination of the degenerate pair gives the same reaction probability. In addition, the symmetric and asymmetric stretching modes of the reactant NH₃ have comparable efficacies on driving the reaction.

Full-dimensional quantum dynamics study of isotope effects for the H2 + NH2/ND2/NHD and H2/D2/HD + NH2 reactions

A full-dimensional quantum dynamical study for the bimolecular reactions of hydrogen molecules with amino radicals for different isotopologues is reported. The nonreactive amino radical is described by two Radau vectors that are very close to the valence bond coordinates. Potential-optimized discrete variable representation basis is used for the vibrational coordinates of the amino radical. Starting from the reaction H₂ + NH₂, we study the isotope effects for the two reagents separately, i.e., H₂ + NH₂/ND₂/NHD and H₂/D₂/HD + NH₂. The effects of different vibrational mode excitations of the reagents on the reactivities are studied. Physical explanations about the isotope effects are also provided thoroughly including the influence of vibrational energy differences between the different isotopologues and the impact of the tunneling effect.

The effect of CO rotation from shaped pulse polarization on reactions that form C2

The effect of CO rotational energy on bimolecular reactions to form electronically excited C₂ is reported here.

Recent advances in quantum scattering calculations on polyatomic bimolecular reactions

This review surveys quantum scattering calculations on chemical reactions of polyatomic molecules in the gas phase published in the last ten years.

Recent Advances in Quantum Dynamics of Bimolecular Reactions

In this review, we survey the latest advances in theoretical understanding of bimolecular reaction dynamics in the past decade. The remarkable recent progress in this field has been driven by more accurate and efficient ab initio electronic structure theory, effective potential-energy surface fitting techniques, and novel quantum scattering algorithms. Quantum mechanical characterization of bimolecular reactions continues to uncover interesting dynamical phenomena in atom-diatom reactions and beyond, reaching an unprecedented level of sophistication. In tandem with experimental explorations, these theoretical developments have greatly advanced our understanding of key issues in reaction dynamics, such as microscopic reaction mechanisms, mode specificity, product energy disposal, influence of reactive resonances, and nonadiabatic effects.

Comparison of experimental and theoretical quantum-state-selected integral cross-sections for the H2O+ + H2 (D2) reactions in the collision energy range of 0.04–10.00 eV

A combined experimental–theoretical study of the rovibrationally state-selected ion–molecule reactions H₂O⁺(X²B₁; v₁⁺v₂⁺v₃⁺; N_Ka+Kc+⁺) + H₂ (D₂) → H₃O⁺ (H₂DO⁺) + H (D), where (v₁⁺v₂⁺v₃⁺) = (000), (020), and (100) and N_Ka+Kc+⁺ = 0₀₀, 1₁₁, and 2₁₁.

Mode specific dynamics in the H2 + SH → H + H2S reaction

Full-dimensional quantum dynamics and quasi-classical trajectory studies indicate strong mode selectivity in the H₂ + SH reaction.