Analyses of the A- X electronic transitions of the CH2XOO·(X = I, Br, Cl) radicals

Huang, Meng

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https://hdl.handle.net/2142/91182 Copy

Description

Title

Analyses of the A- X electronic transitions of the CH2XOO·(X = I, Br, Cl) radicals

Author(s)

Huang, Meng

Contributor(s)

• Miller, Terry A.
• Kline, Neal

Issue Date

2016-06-23

Keyword(s)

Radicals

Abstract

Cavity ringdown, near-infrared spectra have been previously observed following the photolysis of the dihalomethanes(CH${_2}$XI, X = I, Br, Cl) in the presence of O${_2}$ and N${_2}$. In last year's Symposium\footnote{N.~D.~Kline, M.~Huang, T.~A.~Miller, P.~Lolur, R.~Dawes, FD05, \textit{70th International Symposium of Molecular Spectroscopy}(2015)}, we presented evidence that all the spectra could be attributed to the \textit{\~{A}-\~{X}} electronic transition of the appropriate CH${_2}$XOO${\cdot}$ radical. We now present detailed analyses of these spectra. Similar spectral features have been observed for all radicals. The first strong transitions are located around 6800 cm${^{-1}}$, and are assigned as associated with the origin. Other strong transitions are observed about 800 cm${^{-1}}$ blue of the origin, and have a multiple-peak structure similar to the corresponding origin bands. These bands are assigned to be the OO stretch of the \textit{\~{A}-\~{X}} electronic transitions, which are typically strong in the spectra of peroxy radicals, based on electronic structure calculations that provide vibrational frequencies and Franck-Condon factors. One-dimensional calculations of the internal torsion mode are applied to specifically explain the multiple-peak features in both the origin and OO stretch region as series of transitions including sequence bands and other hot bands from the vibrationally excited states of the low-frequency torsion mode in the \textit{\~{X}} state, which are significantly populated at room temperature. Additional bands can be assigned to fundamentals or combination bands of various other \textit{\~{A}} state modes.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

En

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http://hdl.handle.net/2142/91182

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Copyright 2016 by the authors

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