Title: Photodissociation Dynamics of CH₂OO on Multiple Potential Energy Surfaces: Experiment and Theory

Abstract

UV excitation of the CH₂OO Criegee intermediate across most of the broad span of the (B 1A') – (X 1A') spectrum results in prompt dissociation to two energetically accessible asymptotes: O (¹D) + H₂CO (X ¹A₁) and O (³P) + H₂CO (a 3A"). Dissociation proceeds on multiple singlet potential energy surfaces that are coupled by two regions of conical intersection (CoIn). Velocity map imaging (VMI) studies reveal a bimodal total kinetic energy (TKER) distribution for the O (¹D) + H₂CO (X ¹A₁) products with the major and minor components accounting for ca. 40% and ca. 20% on average of the available energy (E_avl), respectively. The unexpected low TKER component corresponds to highly internally excited H₂CO (X ¹A₁) products accommodating ca. 80% of E_avl. Full dimensional trajectory calculations suggest that the bimodal TKER distribution of the O (¹D) + H₂CO (X ¹A₁) products originates from two different dynamical pathways: a primary pathway (69%) evolving through one CoIn region to products and a smaller component (20%) sampling both CoIn regions enroute to products. Those that access both CoIn regions likely give rise to the more highly internally excited H₂CO (X ¹A₁) products. The remaining trajectories (11%) dissociate to O (³P) + H₂COmore » (a ³A") products after traversing through both CoIn regions. Here, the complementary experimental and theoretical investigation provides insight on the photodissociation of CH₂OO via multiple dissociation pathways through two regions of CoIn that control the branching and energy distributions of products.« less

Authors:

Esposito, Vincent J.  ^[1];

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• Search DOE PAGES for ORCID "0000-0001-6035-3869"

Liu, Tianlin  ^[1];

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Wang, Guanghan  ^[1];

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Caracciolo, Adriana  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-2588-7627"

Vansco, Michael F.  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-6189-6272"

Marchetti, Barbara  ^[2];

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• Search DOE PAGES for ORCID "0000-0002-0661-9029"

Karsili, Tolga N. V.  ^[2];

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• Search DOE PAGES for ORCID "0000-0002-0583-3824"

Lester, Marsha I.  ^[1]

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• Search DOE PAGES for ORCID "0000-0003-2367-3497"

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+ Show Author Affiliations

1. Univ. of Pennsylvania, Philadelphia, PA (United States)
2. Univ. of Louisiana, Lafayette, LA (United States)

Publication Date:

Tue Jul 27 00:00:00 EDT 2021

Research Org.:

Univ. of Pennsylvania, Philadelphia, PA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division; National Science Foundation (NSF)

OSTI Identifier:

1865331

Grant/Contract Number:  

FG02-87ER13792; DGE-1845298; CHE-2003422

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory

Additional Journal Information:

Journal Volume: 125; Journal Issue: 30; Journal ID: ISSN 1089-5639

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Computational chemistry; Dissociation; Photodissociation; Bond cleavage; Energy