UV Absorption Spectrum and Photodissociation Channels of the Simplest Criegee Intermediate (CH₂OO)

Abstract

The lowest-lying singlet states of the simplest Criegee intermediate (CH2OO) have been characterized along the O-O dissociation coordinate using explicitly correlated MRCI-F12 electronic structure theory and large active spaces. It is found that a high-level treatment of dynamic electron-correlation is essential to accurately describe these states. a significant well on the B-state is identified at the MRCI-F12 level with an equilibrium structure that differs substantially from that of the ground X-state. This well is presumably responsible for the apparent vibrational structure in some experimental UV absorption spectra, analogous to the structured Huggins band of the iso-electronic ozone. the B-state potential in the Franck-Condon region is sufficiently accurate that an absorption spectrum calculated with a one-dimensional model agrees remarkably well with experiment.

Department(s)

Chemistry

Research Center/Lab(s)

Center for High Performance Computing Research

Keywords and Phrases

Absorption spectra; Electromagnetic wave absorption; Electronic structure; Light absorption; Photodissociation; Criegee intermediates; Electronic structure theory; Equilibrium structures; High-level treatment; Lowest-lying singlet state; One-dimensional model; UV absorption spectrum; Vibrational structures; Absorption spectroscopy; formaldehyde; alkene; ozone; Article; calculation; dissociation; experimental study; geometry; simplest criegee intermediate; ultraviolet spectroscopy; chemistry; photochemistry; ultraviolet spectrophotometry; Alkenes; Ozone; Photochemical Processes; Spectrophotometry, Ultraviolet

International Standard Serial Number (ISSN)

0002-7863

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2015 American Chemical Society (ACS), All rights reserved.

Publication Date

01 Jan 2015

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