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Molecular dynamics in tilted bilayer smectic phases: a proton nuclear magnetic resonance relaxometry study

2001-12Journal article Open access
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dc.contributor.authorCarvalho, A.
dc.contributor.authorSebastião, P. J.
dc.contributor.authorRibeiro, A. C.
dc.contributor.authorNguyen, H. T.
dc.contributor.authorVilfan, M.
dc.date.accessioned2018-09-21T13:09:24Z
dc.date.available2018-09-21T13:09:24Z
dc.date.issued2001-12
dc.description.abstractA proton nuclear magnetic resonance (NMR) relaxation study of molecular dynamics in the liquid crystal 4-octylphenyl 2-chloro-4-(4-cyanobenzoyloxy)benzoate (DB8Cl) is presented. DB8Cl molecules possess a strong polar terminal group and form, in addition to the nematic phase, three different smectic phases: bilayer smectic A, bilayer smectic C, and anticliniclike smectic C phase. The proton spin-lattice relaxation times were measured in all mesophases over a broad frequency range of six decades by applying conventional and fast field-cycling NMR techniques. The parameters obtained in the analysis of the experimental data give quantitative information on molecular motions, particularly for the tilted smectic phases of DB8Cl. In contrast to former conjectures, we found that the low-frequency relaxation in the bilayer smectic C phases results from director fluctuations about the layer normal, which occur without distortion of the layers, and from layer undulations, similar to those in the smectic A phase. In the low-temperature bilayer smectic C phase, a considerable slowing-down of molecular translational diffusion is observed. It confirms indirectly the anticlinic character of this mesophase. Measurements of angular dependence of the relaxation times at 60 MHz support the conclusions obtained from the frequency dispersion data.pt_PT
dc.description.versioninfo:eu-repo/semantics/publishedVersionpt_PT
dc.identifier.citationCarvalho A, Sebastião PJ, Ribeiro AC, Nguyen HT, Vilfan M. Molecular dynamics in tilted bilayer smectic phases: a proton nuclear magnetic resonance relaxometry study. J Chem Phys. 2001;115(22):10484-92.pt_PT
dc.identifier.doi10.1063/1.1413744pt_PT
dc.identifier.urihttp://hdl.handle.net/10400.21/8879
dc.language.isoengpt_PT
dc.peerreviewedyespt_PT
dc.publisherAIP Publishingpt_PT
dc.relation.publisherversionhttps://aip.scitation.org/doi/pdf/10.1063/1.1413744pt_PT
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/4.0/pt_PT
dc.subjectBilayer smectic phasespt_PT
dc.subjectConformational changespt_PT
dc.subjectIntermolecular proton interactionspt_PT
dc.subjectMolecular translational diffusionpt_PT
dc.subjectSpin lattice relaxationpt_PT
dc.subjectMolecular dynamicspt_PT
dc.titleMolecular dynamics in tilted bilayer smectic phases: a proton nuclear magnetic resonance relaxometry studypt_PT
dc.typejournal article
dspace.entity.typePublication
oaire.citation.endPage10492pt_PT
oaire.citation.issue22pt_PT
oaire.citation.startPage10484pt_PT
oaire.citation.titleJournal of Chemical Physicspt_PT
oaire.citation.volume115pt_PT
rcaap.rightsopenAccesspt_PT
rcaap.typearticlept_PT

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