UNRAVELING THE MECHANISM OF THE ELECTRONIC QUENCHING OF NO (A²Σ⁺) WITH C₂H₂

Petit, Andrew S.

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https://hdl.handle.net/2142/122424 Copy

Description

Title

UNRAVELING THE MECHANISM OF THE ELECTRONIC QUENCHING OF NO (A²Σ⁺) WITH C₂H₂

Author(s)

Petit, Andrew S.

Contributor(s)

Jones, Ken

Issue Date

2023-06-23

Keyword(s)

Photodissociation and photochemistry

Abstract

NO is an important reactive intermediate in combustion and atmospheric chemistry. The experimental detection of NO commonly utilizes laser-induced fluorescence (LIF) on the A²Σ⁺ ← X²Σ transition band. However, the electronic quenching of NO (A²Σ⁺) with other molecular species provides alternative photochemical pathways that compete with fluorescence. Prior experimental studies have demonstrated that collisions with C₂H₂ are effective at driving the non-radiative relaxation of NO (A²Σ⁺). Moreover, H-atom production has been observed in this electronic quenching. However, no detailed experimental or theoretical studies have been performed on this system, and the specific photochemical pathways of NO (A²Σ⁺)+C₂H₂ remain unexplored. Here, we describe the development of high-quality potential energy surfaces (PESs) that provide new physical insights into the long-range interactions and conical intersections that facilitate the electronic quenching of NO (A²Σ⁺) by C₂H₂. The PESs are calculated at the EOM-EA-CCSD/d-aug-cc-pVTZ//EOM-EA-CCSD/aug-cc-pVDZ level of theory, an approach that ensures a balanced treatment of the valence and Rydberg electronic states as well as an accurate description of the open-shell character of NO. We demonstrate that intermolecular interactions between NO (A²Σ⁺) and C₂H₂ cause C₂H₂ to isomerize into its trans-bent confirmation. We further identify a downhill pathway for internal conversion. Finally, we are beginning to explore the role that low-lying electronic excited states of C₂H₂ play in the electronic quenching of NO (A²Σ⁺) by C₂H₂. Our work informs future velocity-map imaging experiments and non-adiabatic dynamics simulations on this system.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Language

eng

Handle URL

https://hdl.handle.net/2142/122424

DOI

https://doi.org/10.15278/isms.2023.6715

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