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dc.contributor.authorOsior, Agnieszka
dc.contributor.authorKalicki, Przemysław
dc.contributor.authorKamieński, Bohdan
dc.contributor.authorSzymański, Sławomir
dc.contributor.authorBernatowicz, Piotr
dc.contributor.authorShkurenko, Aleksander
dc.date.accessioned2017-03-20T08:46:09Z
dc.date.available2017-03-20T08:46:09Z
dc.date.issued2017-03-14
dc.identifier.citationOsior A, Kalicki P, Kamieński B, Szymański S, Bernatowicz P, et al. (2017) Nonclassical dynamics of the methyl group in 1,1,1-triphenylethane. Evidence from powder 1H NMR spectra. The Journal of Chemical Physics 146: 104504. Available: http://dx.doi.org/10.1063/1.4978226.
dc.identifier.issn0021-9606
dc.identifier.issn1089-7690
dc.identifier.doi10.1063/1.4978226
dc.identifier.urihttp://hdl.handle.net/10754/623041
dc.description.abstractAccording to the damped quantum rotation (DQR) theory, hindered rotation of methyl groups, evidenced in nuclear magnetic resonance (NMR) line shapes, is a nonclassical process. It comprises a number of quantum-rate processes measured by two different quantum-rate constants. The classical jump model employing only one rate constant is reproduced if these quantum constants happen to be equal. The values of their ratio, or the nonclassicallity coefficient, determined hitherto from NMR spectra of single crystals and solutions range from about 1.20 to 1.30 in the latter case to above 5.0 in the former, with the value of 1 corresponding to the jump model. Presently, first systematic investigations of the DQR effects in wide-line NMR spectra of a powder sample are reported. For 1,1,1-triphenylethane deuterated in the aromatic positions, the relevant line-shape effects were monitored in the range 99–121 K. The values of the nonclassicality coefficient dropping from 2.7 to 1.7 were evaluated in line shape fits to the experimental powder spectra from the range 99–108 K. At these temperatures, the fits with the conventional line-shape model are visibly inferior to the DQR fits. Using a theoretical model reported earlier, a semiquantitative interpretation of the DQR parameters evaluated from the spectra is given. It is shown that the DQR effects as such can be detected in wide-line NMR spectra of powdered samples, which are relatively facile to measure. However, a fully quantitative picture of these effects can only be obtained from the much more demanding experiments on single crystals.
dc.description.sponsorshipP.B., A.O., and S.S. acknowledge partial financial support of this work by the National Center of Science (NCN Grant No. 2012/05/B/ST4/00103).
dc.publisherAIP Publishing
dc.relation.urlhttp://aip.scitation.org/doi/10.1063/1.4978226
dc.rightsThis article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. The following article appeared in The Journal of Chemical Physics and may be found at http://doi.org/10.1063/1.4978226.
dc.titleNonclassical dynamics of the methyl group in 1,1,1-triphenylethane. Evidence from powder 1H NMR spectra
dc.typeArticle
dc.contributor.departmentAdvanced Membranes and Porous Materials Research Center
dc.contributor.departmentFunctional Materials Design, Discovery and Development (FMD3)
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Division
dc.identifier.journalThe Journal of Chemical Physics
dc.eprint.versionPublisher's Version/PDF
dc.contributor.institutionInstitute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warszawa, Poland
dc.contributor.institutionInstitute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warszawa, Polan
kaust.personShkurenko, Aleksander
refterms.dateFOA2018-03-14T00:00:00Z


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