CW- and pulsed-EPR of carbonaceous matter in primitive meteorites: Solving a lineshape paradox
Insoluble organic matter (IOM) of Orgueil and Tagish Lake meteorites are studied by CW-EPR and pulsed-EPR spectroscopies. The EPR line is due to polycyclic paramagnetic moieties concentrated in defect-rich regions of the IOM, with concentrations of the order of 4 × 1019 spin/g. CW-EPR reveals two ty...
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ftunivlilleoa:oai:lilloa.univ-lille.fr:20.500.12210/39635 2024-09-15T18:38:30+00:00 CW- and pulsed-EPR of carbonaceous matter in primitive meteorites: Solving a lineshape paradox Delpoux, Olivier Gourier, Didier Binet, Laurent Vezin, Herve Derenne, Sylvie Robert, François Université de Lille CNRS Chimie organique et macromoléculaire COM 2021-10-07T14:04:24Z https://hdl.handle.net/20.500.12210/39635 Anglais eng Elsevier BV 10.1016/j.saa.2007.09.045 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy http://hdl.handle.net/20.500.12210/39635 info:eu-repo/semantics/closedAccess Article original 2021 ftunivlilleoa https://doi.org/20.500.12210/39635 2024-07-10T03:31:43Z Insoluble organic matter (IOM) of Orgueil and Tagish Lake meteorites are studied by CW-EPR and pulsed-EPR spectroscopies. The EPR line is due to polycyclic paramagnetic moieties concentrated in defect-rich regions of the IOM, with concentrations of the order of 4 × 1019 spin/g. CW-EPR reveals two types of paramagnetic defects: centres with S = 1/2, and centres with S = 0 ground state and thermally accessible triple state S = 1. In spite of the Lorentzian shape of the EPR and its narrowing upon increasing the spin concentration, the EPR line is not in the exchange narrowing regime as previously deduced from multi-frequency CW-EPR [L. Binet, D. Gourier, Appl. Magn. Reson. 30 (2006) 207–231]. It is inhomogeneously broadened as demonstrated by the presence of nuclear modulations in the spin-echo decay. The line narrowing, similar to an exchange narrowing effect, is the result of an increasing contribution of the narrow line of the triplet state centres in addition to the broader line of doublet states. Hyperfine sublevel correlation spectroscopy (HYSCORE) of hydrogen and 13C nuclei indicates that IOMradical dot centres are small polycyclic moieties that are moderately branched with aliphatic chains, as shown by the presence of aromatic hydrogen atoms. On the contrary the lack of such aromatic hydrogen in triplet states suggests that these radicals are most probably highly branched. Paramagnetic centres are considerably enriched in deuterium, with D/H ≈ 1.5 ± 0.5 × 10−2 of the order of values existing in interstellar medium. 69;5 Article in Journal/Newspaper Tagish LillOA (Lille Open Archive - Université de Lille) |
institution |
Open Polar |
collection |
LillOA (Lille Open Archive - Université de Lille) |
op_collection_id |
ftunivlilleoa |
language |
English |
description |
Insoluble organic matter (IOM) of Orgueil and Tagish Lake meteorites are studied by CW-EPR and pulsed-EPR spectroscopies. The EPR line is due to polycyclic paramagnetic moieties concentrated in defect-rich regions of the IOM, with concentrations of the order of 4 × 1019 spin/g. CW-EPR reveals two types of paramagnetic defects: centres with S = 1/2, and centres with S = 0 ground state and thermally accessible triple state S = 1. In spite of the Lorentzian shape of the EPR and its narrowing upon increasing the spin concentration, the EPR line is not in the exchange narrowing regime as previously deduced from multi-frequency CW-EPR [L. Binet, D. Gourier, Appl. Magn. Reson. 30 (2006) 207–231]. It is inhomogeneously broadened as demonstrated by the presence of nuclear modulations in the spin-echo decay. The line narrowing, similar to an exchange narrowing effect, is the result of an increasing contribution of the narrow line of the triplet state centres in addition to the broader line of doublet states. Hyperfine sublevel correlation spectroscopy (HYSCORE) of hydrogen and 13C nuclei indicates that IOMradical dot centres are small polycyclic moieties that are moderately branched with aliphatic chains, as shown by the presence of aromatic hydrogen atoms. On the contrary the lack of such aromatic hydrogen in triplet states suggests that these radicals are most probably highly branched. Paramagnetic centres are considerably enriched in deuterium, with D/H ≈ 1.5 ± 0.5 × 10−2 of the order of values existing in interstellar medium. 69;5 |
author2 |
Université de Lille CNRS Chimie organique et macromoléculaire COM |
format |
Article in Journal/Newspaper |
author |
Delpoux, Olivier Gourier, Didier Binet, Laurent Vezin, Herve Derenne, Sylvie Robert, François |
spellingShingle |
Delpoux, Olivier Gourier, Didier Binet, Laurent Vezin, Herve Derenne, Sylvie Robert, François CW- and pulsed-EPR of carbonaceous matter in primitive meteorites: Solving a lineshape paradox |
author_facet |
Delpoux, Olivier Gourier, Didier Binet, Laurent Vezin, Herve Derenne, Sylvie Robert, François |
author_sort |
Delpoux, Olivier |
title |
CW- and pulsed-EPR of carbonaceous matter in primitive meteorites: Solving a lineshape paradox |
title_short |
CW- and pulsed-EPR of carbonaceous matter in primitive meteorites: Solving a lineshape paradox |
title_full |
CW- and pulsed-EPR of carbonaceous matter in primitive meteorites: Solving a lineshape paradox |
title_fullStr |
CW- and pulsed-EPR of carbonaceous matter in primitive meteorites: Solving a lineshape paradox |
title_full_unstemmed |
CW- and pulsed-EPR of carbonaceous matter in primitive meteorites: Solving a lineshape paradox |
title_sort |
cw- and pulsed-epr of carbonaceous matter in primitive meteorites: solving a lineshape paradox |
publisher |
Elsevier BV |
publishDate |
2021 |
url |
https://hdl.handle.net/20.500.12210/39635 |
genre |
Tagish |
genre_facet |
Tagish |
op_relation |
10.1016/j.saa.2007.09.045 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy http://hdl.handle.net/20.500.12210/39635 |
op_rights |
info:eu-repo/semantics/closedAccess |
op_doi |
https://doi.org/20.500.12210/39635 |
_version_ |
1810482902716121088 |