Quantum mechanical alternative to Arrhenius equation in the interpretation of proton spin-lattice relaxation data for the methyl groups in solids

Handle URI:
http://hdl.handle.net/10754/579435
Title:
Quantum mechanical alternative to Arrhenius equation in the interpretation of proton spin-lattice relaxation data for the methyl groups in solids
Authors:
Bernatowicz, Piotr; Shkurenko, Aleksander ( 0000-0001-7136-2277 ) ; Osior, Agnieszka; Kamieński, Bohdan; Szymański, Sławomir
Abstract:
Theory of nuclear spin-lattice relaxation in methyl groups in solids has been a recurring problem in nuclear magnetic resonance (NMR) spectroscopy. The current view is that, except for extreme cases of low torsional barriers where special quantum effects are at stake, the relaxation behaviour of the nuclear spins in methyl groups is controlled by thermally activated classical jumps of the methyl group between its three orientations. The temperature effects on the relaxation rates can be modelled by Arrhenius behaviour of the correlation time of the jump process. The entire variety of relaxation effects in protonated methyl groups has recently been given a consistently quantum mechanical explanation not invoking the jump model regardless of the temperature range. It exploits the damped quantum rotation (DQR) theory originally developed to describe NMR line shape effects for hindered methyl groups. In the DQR model, the incoherent dynamics of the methyl group include two quantum rate, i.e., coherence-damping processes. For proton relaxation only one of these processes is relevant. In this paper, temperature-dependent proton spin-lattice relaxation data for the methyl groups in polycrystalline methyltriphenyl silane and methyltriphenyl germanium, both deuterated in aromatic positions, are reported and interpreted in terms of the DQR model. A comparison with the conventional approach exploiting the phenomenological Arrhenius equation is made. The present observations provide further indications that incoherent motions of molecular moieties in condensed phase can retain quantum character over much broad temperature range than is commonly thought.
KAUST Department:
Functional Materials Design, Discovery and Development (FMD3); Advanced Membranes and Porous Materials Research Center; Physical Sciences and Engineering (PSE) Division
Citation:
Quantum mechanical alternative to Arrhenius equation in the interpretation of proton spin-lattice relaxation data for the methyl groups in solids 2015 Phys. Chem. Chem. Phys.
Publisher:
Royal Society of Chemistry (RSC)
Journal:
Phys. Chem. Chem. Phys.
Issue Date:
1-Oct-2015
DOI:
10.1039/C5CP04924E
Type:
Article
ISSN:
1463-9076; 1463-9084
Is Supplemented By:
Bernatowicz, P., Shkurenko, A., Osior, A., Kamieński, B., & Szymański, S. (2015). CCDC 1416891: Experimental Crystal Structure Determination [Data set]. Cambridge Crystallographic Data Centre. https://doi.org/10.5517/cc1jkd5n; DOI:10.5517/cc1jkd5n; HANDLE:http://hdl.handle.net/10754/624457
Additional Links:
http://pubs.rsc.org/en/Content/ArticleLanding/2015/CP/C5CP04924E
Appears in Collections:
Articles; Advanced Membranes and Porous Materials Research Center; Physical Sciences and Engineering (PSE) Division; Functional Materials Design, Discovery and Development (FMD3)

Full metadata record

DC FieldValue Language
dc.contributor.authorBernatowicz, Piotren
dc.contributor.authorShkurenko, Aleksanderen
dc.contributor.authorOsior, Agnieszkaen
dc.contributor.authorKamieński, Bohdanen
dc.contributor.authorSzymański, Sławomiren
dc.date.accessioned2015-10-07T09:08:28Zen
dc.date.available2015-10-07T09:08:28Zen
dc.date.issued2015-10-01en
dc.identifier.citationQuantum mechanical alternative to Arrhenius equation in the interpretation of proton spin-lattice relaxation data for the methyl groups in solids 2015 Phys. Chem. Chem. Phys.en
dc.identifier.issn1463-9076en
dc.identifier.issn1463-9084en
dc.identifier.doi10.1039/C5CP04924Een
dc.identifier.urihttp://hdl.handle.net/10754/579435en
dc.description.abstractTheory of nuclear spin-lattice relaxation in methyl groups in solids has been a recurring problem in nuclear magnetic resonance (NMR) spectroscopy. The current view is that, except for extreme cases of low torsional barriers where special quantum effects are at stake, the relaxation behaviour of the nuclear spins in methyl groups is controlled by thermally activated classical jumps of the methyl group between its three orientations. The temperature effects on the relaxation rates can be modelled by Arrhenius behaviour of the correlation time of the jump process. The entire variety of relaxation effects in protonated methyl groups has recently been given a consistently quantum mechanical explanation not invoking the jump model regardless of the temperature range. It exploits the damped quantum rotation (DQR) theory originally developed to describe NMR line shape effects for hindered methyl groups. In the DQR model, the incoherent dynamics of the methyl group include two quantum rate, i.e., coherence-damping processes. For proton relaxation only one of these processes is relevant. In this paper, temperature-dependent proton spin-lattice relaxation data for the methyl groups in polycrystalline methyltriphenyl silane and methyltriphenyl germanium, both deuterated in aromatic positions, are reported and interpreted in terms of the DQR model. A comparison with the conventional approach exploiting the phenomenological Arrhenius equation is made. The present observations provide further indications that incoherent motions of molecular moieties in condensed phase can retain quantum character over much broad temperature range than is commonly thought.en
dc.language.isoenen
dc.publisherRoyal Society of Chemistry (RSC)en
dc.relation.urlhttp://pubs.rsc.org/en/Content/ArticleLanding/2015/CP/C5CP04924Een
dc.rightsArchived with thanks to Phys. Chem. Chem. Phys.en
dc.titleQuantum mechanical alternative to Arrhenius equation in the interpretation of proton spin-lattice relaxation data for the methyl groups in solidsen
dc.typeArticleen
dc.contributor.departmentFunctional Materials Design, Discovery and Development (FMD3)en
dc.contributor.departmentAdvanced Membranes and Porous Materials Research Centeren
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.identifier.journalPhys. Chem. Chem. Phys.en
dc.eprint.versionPost-printen
dc.contributor.institutionInstitute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Polanden
dc.contributor.institutionInstitute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Polanden
dc.contributor.affiliationKing Abdullah University of Science and Technology (KAUST)en
kaust.authorShkurenko, Aleksanderen
dc.relation.isSupplementedByBernatowicz, P., Shkurenko, A., Osior, A., Kamieński, B., & Szymański, S. (2015). CCDC 1416891: Experimental Crystal Structure Determination [Data set]. Cambridge Crystallographic Data Centre. https://doi.org/10.5517/cc1jkd5nen
dc.relation.isSupplementedByDOI:10.5517/cc1jkd5nen
dc.relation.isSupplementedByHANDLE:http://hdl.handle.net/10754/624457en
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