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Site-specific hydrogen-atom elimination in photoexcited ethyl radical.


ABSTRACT: The photochemistry of the ethyl radical following excitation to the 3p Rydberg state is investigated in a joint experimental and theoretical study. Velocity map images for hydrogen atoms detected from photoexcited isotopologues CH3CH2, CH3CD2 and CD3CH2 at ?201 nm, are discussed along with high-level ab initio electronic structure calculations of potential energy curves and non-adiabatic coupling matrix elements (NACME). A novel mechanism governed by a conical intersection allowing prompt site-specific hydrogen-atom elimination is presented and discussed. For this mechanism to occur, an initial ro-vibrational excitation is allocated to the radical permitting to access this reaction pathway and thus to control the ethyl photochemistry. While hydrogen-atom elimination from cold ethyl radicals occurs through internal conversion into lower electronic states followed by slow statistical dissociation, prompt site-specific C? elimination into CH3CH + H, occurring through a fast non-adiabatic crossing to a valence bound state followed by dissociation through a conical intersection, is accessed by means of an initial ro-vibrational energy content into the radical. The role of a particularly effective vibrational promoting mode in this prompt photochemical reaction pathway is discussed.

SUBMITTER: Chicharro DV 

PROVIDER: S-EPMC6610558 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature

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Site-specific hydrogen-atom elimination in photoexcited ethyl radical.

Chicharro David V DV   Poullain Sonia Marggi SM   Zanchet Alexandre A   Bouallagui Aymen A   García-Vela Alberto A   Senent María L ML   Rubio-Lago Luis L   Bañares Luis L  

Chemical science 20190522 26


The photochemistry of the ethyl radical following excitation to the 3p Rydberg state is investigated in a joint experimental and theoretical study. Velocity map images for hydrogen atoms detected from photoexcited isotopologues CH<sub>3</sub>CH<sub>2</sub>, CH<sub>3</sub>CD<sub>2</sub> and CD<sub>3</sub>CH<sub>2</sub> at ∼201 nm, are discussed along with high-level <i>ab initio</i> electronic structure calculations of potential energy curves and non-adiabatic coupling matrix elements (NACME). A  ...[more]

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