Effects of symmetry, methyl groups and serendipity on intramolecular vibrational energy dispersal

We consider two key parameters that have been proposed to be important for vibrational energy delocalization, closely related to intramolecular vibrational redistribution (IVR), in molecules. These parameters are the symmetry of the molecule, and the presence of torsional (internal rotor) modes of a...

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Main Authors:	Tuttle, William D., Gardner, Adrian M., Whalley, Laura E., Kemp, David J., Wright, Timothy G.
Format:	Article
Language:	English
Published:	Royal Society of Chemistry 2018
Online Access:	http://eprints.nottingham.ac.uk/52334/ http://eprints.nottingham.ac.uk/52334/ http://eprints.nottingham.ac.uk/52334/ http://eprints.nottingham.ac.uk/52334/1/Tim%20Wright%20Effects%20of%20symmetry%2C%20methyl%20groups%20and%20serendipity.pdf

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spelling	nottingham-523342018-06-12T03:26:28Z http://eprints.nottingham.ac.uk/52334/ Effects of symmetry, methyl groups and serendipity on intramolecular vibrational energy dispersal Tuttle, William D. Gardner, Adrian M. Whalley, Laura E. Kemp, David J. Wright, Timothy G. We consider two key parameters that have been proposed to be important for vibrational energy delocalization, closely related to intramolecular vibrational redistribution (IVR), in molecules. These parameters are the symmetry of the molecule, and the presence of torsional (internal rotor) modes of a methyl group. We consider four para-disubstituted benzene molecules and examine their vibrational character. The molecules selected are para-difluorobenzene, para-chlorofluorobenzene, para-fluorotoluene, and para-xylene. This set of molecules allows the above parameters to be assessed in a systematic way. The probe we use is zero-electron-kinetic-energy (ZEKE) spectroscopy, which is employed in a resonant scheme, where the intermediate levels are selected vibrational levels of the S1 excited electronic state, with wavenumbers up to 1300 cm 1. We conclude that symmetry, and the presence of a methyl groups, do indeed have a profound effect on “restricted” IVR at low energies. This is underpinned by serendipitous coincidences in the energies of the levels, owing to small shifts in vibrational wavenumbers. Additionally, methyl groups play an important role in opening up new routes for coupling between vibrations of different symmetry, and this is critical in the transition to “statistical” IVR at lower energies for molecules that contain them. Further, the presence of two methyl groups in the symmetrically-substituted p-xylene causes more widespread IVR than does the single methyl group in the asymmetrically-substituted p-fluorotoluene. Royal Society of Chemistry 2018-06-09 Article PeerReviewed application/pdf en http://eprints.nottingham.ac.uk/52334/1/Tim%20Wright%20Effects%20of%20symmetry%2C%20methyl%20groups%20and%20serendipity.pdf Tuttle, William D. and Gardner, Adrian M. and Whalley, Laura E. and Kemp, David J. and Wright, Timothy G. (2018) Effects of symmetry, methyl groups and serendipity on intramolecular vibrational energy dispersal. Physical Chemistry Chemical Physics . ISSN 1463-9084 http://pubs.rsc.org/en/content/articlelanding/2018/cp/c8cp02757a#!divAbstract doi:10.1039/C8CP02757A doi:10.1039/C8CP02757A
repository_type	Digital Repository
institution_category	Local University
institution	University of Nottingham Malaysia Campus
building	Nottingham Research Data Repository
collection	Online Access
language	English
description	We consider two key parameters that have been proposed to be important for vibrational energy delocalization, closely related to intramolecular vibrational redistribution (IVR), in molecules. These parameters are the symmetry of the molecule, and the presence of torsional (internal rotor) modes of a methyl group. We consider four para-disubstituted benzene molecules and examine their vibrational character. The molecules selected are para-difluorobenzene, para-chlorofluorobenzene, para-fluorotoluene, and para-xylene. This set of molecules allows the above parameters to be assessed in a systematic way. The probe we use is zero-electron-kinetic-energy (ZEKE) spectroscopy, which is employed in a resonant scheme, where the intermediate levels are selected vibrational levels of the S1 excited electronic state, with wavenumbers up to 1300 cm 1. We conclude that symmetry, and the presence of a methyl groups, do indeed have a profound effect on “restricted” IVR at low energies. This is underpinned by serendipitous coincidences in the energies of the levels, owing to small shifts in vibrational wavenumbers. Additionally, methyl groups play an important role in opening up new routes for coupling between vibrations of different symmetry, and this is critical in the transition to “statistical” IVR at lower energies for molecules that contain them. Further, the presence of two methyl groups in the symmetrically-substituted p-xylene causes more widespread IVR than does the single methyl group in the asymmetrically-substituted p-fluorotoluene.
format	Article
author	Tuttle, William D. Gardner, Adrian M. Whalley, Laura E. Kemp, David J. Wright, Timothy G.
spellingShingle	Tuttle, William D. Gardner, Adrian M. Whalley, Laura E. Kemp, David J. Wright, Timothy G. Effects of symmetry, methyl groups and serendipity on intramolecular vibrational energy dispersal
author_facet	Tuttle, William D. Gardner, Adrian M. Whalley, Laura E. Kemp, David J. Wright, Timothy G.
author_sort	Tuttle, William D.
title	Effects of symmetry, methyl groups and serendipity on intramolecular vibrational energy dispersal
title_short	Effects of symmetry, methyl groups and serendipity on intramolecular vibrational energy dispersal
title_full	Effects of symmetry, methyl groups and serendipity on intramolecular vibrational energy dispersal
title_fullStr	Effects of symmetry, methyl groups and serendipity on intramolecular vibrational energy dispersal
title_full_unstemmed	Effects of symmetry, methyl groups and serendipity on intramolecular vibrational energy dispersal
title_sort	effects of symmetry, methyl groups and serendipity on intramolecular vibrational energy dispersal
publisher	Royal Society of Chemistry
publishDate	2018
url	http://eprints.nottingham.ac.uk/52334/ http://eprints.nottingham.ac.uk/52334/ http://eprints.nottingham.ac.uk/52334/ http://eprints.nottingham.ac.uk/52334/1/Tim%20Wright%20Effects%20of%20symmetry%2C%20methyl%20groups%20and%20serendipity.pdf
first_indexed	2018-09-06T14:26:32Z
last_indexed	2018-09-06T14:26:32Z
_version_	1610868580915609600

Effects of symmetry, methyl groups and serendipity on intramolecular vibrational energy dispersal

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