Ultraviolet Photodissociation Dynamics Of The Cyclohexyl Radical

Lucas, Michael

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https://hdl.handle.net/2142/51125 Copy

Description

Title

Ultraviolet Photodissociation Dynamics Of The Cyclohexyl Radical

Author(s)

Lucas, Michael

Contributor(s)

• Zhang, Jingsong
• Liu, Yanlin

Issue Date

2014-06-17

Keyword(s)

Mini-symposium: Spectroscopy in Kinetics and Dynamics

Abstract

The ultraviolet (UV) photodissociation dynamics of the cyclohexyl (\textit{c}-\chem{C_6H_11}) radical was studied for the first time using the high-\textit{n} Rydberg atom time-of-flight (HRTOF) technique. The cyclohexyl radical was produced by the 193 nm photodissociation of chlorocyclohexane and bromocyclohexane and was examined in the photolysis region of 232-262 nm. The H-atom photofragment yield (PFY) spectrum contains a broad peak centering around 250 nm, in good agreement with the UV absorption spectra of cyclohexyl. The translational energy distributions of the H-atom loss product channel, \textit{P}(\textit{E}$_{T}$)’s, show a large translational energy release peaking at ~ 45 kcal/mol. The fraction of average translational energy in the total excess energy, $<$\textit{f}$_{T}$$>$, is in the range of 0.45-0.57 from 232-262 nm. The H-atom product angular distribution is anisotropic with a positive $\beta$ parameter in the range of 0.3-1.0, indicating a dissociation time scale faster than one rotation period of the radical. The translational energy release and anisotropy of the H-atom loss product channel are significantly larger than those expected for a statistical unimolecular dissociation of a hot radical, thus showing a non-statistical dissociation mechanism of this large radical. The dissociation mechanism is consistent with direct dissociation on a repulsive excited state surface or on the repulsive part of the ground state surface to produce cyclohexene + H, possibly mediated by conical intersection.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

English

Permalink

http://hdl.handle.net/2142/51125

DOI

https://doi.org/10.15278/isms.2014.TC04

Copyright and License Information

Copyright 2014 by the authors. Licensed under a Creative Commons Attribution 4.0 International License. http://creativecommons.org/licenses/by/4.0/

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