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Probing ultrafast C–Br bond fission in the UV photochemistry of bromoform with core-to-valence transient absorption spectroscopy
UV pump–extreme UV (XUV) probe femtosecond transient absorption spectroscopy is used to study the 268 nm induced photodissociation dynamics of bromoform (CHBr(3)). Core-to-valence transitions at the Br(3d) absorption edge (∼70 eV) provide an atomic scale perspective of the reaction, sensitive to cha...
Autores principales: | , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
American Crystallographic Association
2019
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6800284/ https://www.ncbi.nlm.nih.gov/pubmed/31649963 http://dx.doi.org/10.1063/1.5113798 |
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author | Toulson, Benjamin W. Borgwardt, Mario Wang, Han Lackner, Florian Chatterley, Adam S. Pemmaraju, C. D. Neumark, Daniel M. Leone, Stephen R. Prendergast, David Gessner, Oliver |
author_facet | Toulson, Benjamin W. Borgwardt, Mario Wang, Han Lackner, Florian Chatterley, Adam S. Pemmaraju, C. D. Neumark, Daniel M. Leone, Stephen R. Prendergast, David Gessner, Oliver |
author_sort | Toulson, Benjamin W. |
collection | PubMed |
description | UV pump–extreme UV (XUV) probe femtosecond transient absorption spectroscopy is used to study the 268 nm induced photodissociation dynamics of bromoform (CHBr(3)). Core-to-valence transitions at the Br(3d) absorption edge (∼70 eV) provide an atomic scale perspective of the reaction, sensitive to changes in the local valence electronic structure, with ultrafast time resolution. The XUV spectra track how the singly occupied molecular orbitals of transient electronic states develop throughout the C–Br bond fission, eventually forming radical Br and CHBr(2) products. Complementary ab initio calculations of XUV spectral fingerprints are performed for transient atomic arrangements obtained from sampling excited-state molecular dynamics simulations. C–Br fission along an approximately [Formula: see text] symmetrical reaction pathway leads to a continuous change of electronic orbital characters and atomic arrangements. Two timescales dominate changes in the transient absorption spectra, reflecting the different characteristic motions of the light C and H atoms and the heavy Br atoms. Within the first 40 fs, distortion from [Formula: see text] symmetry to form a quasiplanar CHBr(2) by the displacement of the (light) CH moiety causes significant changes to the valence electronic structure. Displacement of the (heavy) Br atoms is delayed and requires up to ∼300 fs to form separate Br + CHBr(2) products. We demonstrate that transitions between the valence-excited (initial) and valence + core-excited (final) state electronic configurations produced by XUV absorption are sensitive to the localization of valence orbitals during bond fission. The change in valence electron-core hole interaction provides a physical explanation for spectral shifts during the process of bond cleavage. |
format | Online Article Text |
id | pubmed-6800284 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2019 |
publisher | American Crystallographic Association |
record_format | MEDLINE/PubMed |
spelling | pubmed-68002842019-10-24 Probing ultrafast C–Br bond fission in the UV photochemistry of bromoform with core-to-valence transient absorption spectroscopy Toulson, Benjamin W. Borgwardt, Mario Wang, Han Lackner, Florian Chatterley, Adam S. Pemmaraju, C. D. Neumark, Daniel M. Leone, Stephen R. Prendergast, David Gessner, Oliver Struct Dyn ARTICLES UV pump–extreme UV (XUV) probe femtosecond transient absorption spectroscopy is used to study the 268 nm induced photodissociation dynamics of bromoform (CHBr(3)). Core-to-valence transitions at the Br(3d) absorption edge (∼70 eV) provide an atomic scale perspective of the reaction, sensitive to changes in the local valence electronic structure, with ultrafast time resolution. The XUV spectra track how the singly occupied molecular orbitals of transient electronic states develop throughout the C–Br bond fission, eventually forming radical Br and CHBr(2) products. Complementary ab initio calculations of XUV spectral fingerprints are performed for transient atomic arrangements obtained from sampling excited-state molecular dynamics simulations. C–Br fission along an approximately [Formula: see text] symmetrical reaction pathway leads to a continuous change of electronic orbital characters and atomic arrangements. Two timescales dominate changes in the transient absorption spectra, reflecting the different characteristic motions of the light C and H atoms and the heavy Br atoms. Within the first 40 fs, distortion from [Formula: see text] symmetry to form a quasiplanar CHBr(2) by the displacement of the (light) CH moiety causes significant changes to the valence electronic structure. Displacement of the (heavy) Br atoms is delayed and requires up to ∼300 fs to form separate Br + CHBr(2) products. We demonstrate that transitions between the valence-excited (initial) and valence + core-excited (final) state electronic configurations produced by XUV absorption are sensitive to the localization of valence orbitals during bond fission. The change in valence electron-core hole interaction provides a physical explanation for spectral shifts during the process of bond cleavage. American Crystallographic Association 2019-10-11 /pmc/articles/PMC6800284/ /pubmed/31649963 http://dx.doi.org/10.1063/1.5113798 Text en © 2019 Author(s). 2329-7778/2019/6(5)/054304/14 All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). |
spellingShingle | ARTICLES Toulson, Benjamin W. Borgwardt, Mario Wang, Han Lackner, Florian Chatterley, Adam S. Pemmaraju, C. D. Neumark, Daniel M. Leone, Stephen R. Prendergast, David Gessner, Oliver Probing ultrafast C–Br bond fission in the UV photochemistry of bromoform with core-to-valence transient absorption spectroscopy |
title | Probing ultrafast C–Br bond fission in the UV photochemistry of bromoform with core-to-valence transient absorption spectroscopy |
title_full | Probing ultrafast C–Br bond fission in the UV photochemistry of bromoform with core-to-valence transient absorption spectroscopy |
title_fullStr | Probing ultrafast C–Br bond fission in the UV photochemistry of bromoform with core-to-valence transient absorption spectroscopy |
title_full_unstemmed | Probing ultrafast C–Br bond fission in the UV photochemistry of bromoform with core-to-valence transient absorption spectroscopy |
title_short | Probing ultrafast C–Br bond fission in the UV photochemistry of bromoform with core-to-valence transient absorption spectroscopy |
title_sort | probing ultrafast c–br bond fission in the uv photochemistry of bromoform with core-to-valence transient absorption spectroscopy |
topic | ARTICLES |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6800284/ https://www.ncbi.nlm.nih.gov/pubmed/31649963 http://dx.doi.org/10.1063/1.5113798 |
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