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dc.contributor.authorVIJ, JAGDISHen
dc.contributor.authorFUKUDA, ATSUOen
dc.date.accessioned2008-06-24T12:36:13Z
dc.date.available2008-06-24T12:36:13Z
dc.date.issued2006en
dc.date.submitted2006en
dc.identifier.citationN. Hayashi, T. Kato, A. Kocot, A. Fukuda, J. K. Vij, G. Heppke, S. Kwada, and S. Kondoh, Experimental demonstration, using polarized Raman and infrared spectroscopy that both conventional and de Vries smectic_A phase may exist in smectic liquid crystals with a first-order A-C* transition, Physical Review E, 74, 2006, 051706-1 - 051706-11en
dc.identifier.otherYen
dc.identifier.urihttp://hdl.handle.net/2262/17667
dc.descriptionPUBLISHEDen
dc.description.abstractTwo models exist for the orientational distribution of the long molecular axes in smectic-A liquid crystals: the conventional unimodal distribution and the ?cone-shaped? de Vries distribution. The de Vries hypothesis provides a plausible picture of how, at a molecular level, a first-order Sm-A to Sm-C* transition may occur, especially if there is little or no concomitant shrinkage of the layer spacing. This work investigates two materials with such transitions: C7 and TSiKN65. The azimuthal distribution of in-layer directors is probed using IR and polarized Raman spectroscopy, which allows us to obtain orientational order parameters. In C7, we observe a discontinuous change in the order parameter, the magnitude of which is small compared with the corresponding change in the in-layer director tilt angle . Assuming that the smectic-A liquid crystal is of the de Vries type, we calculate the required to reproduce the apparent order parameter P2 app, obtained from IR, by using the true order parameter P2 , obtained from polarized Raman scattering. The results indicate that, for C7, the tilt angle so calculated is much smaller than that in the Sm-C* angle and hence de Vries behavior may not be the appropriate explanation in this case. Conversely, we find that TSiKN65 shows a different behavior to C7, which can be explained in terms of the de Vries concept. Thus, we conclude that either type of distribution may exist in Sm-A phases which undergo a first-order transition to the Sm-C* phase. We also discuss the changes in the smectic layer spacing and the orientational order parameters across the Sm-ASm- C* phase transition, together with changes in birefringence with applied electric field.en
dc.description.sponsorshipJ.K.V. thanks the Science Foundation of Ireland for Grant No. SFI 02/In.1/I031 for funding the research and visit of N.H. to Dublin and the visiting appointment of A. Kocot. M.J.L. thanks the European Union for funding under the SAMPA programme HPRN-CT-2002-00202. Atsuo Fukuda?s research at Trinity College Dublin was funded by Grant No. SFI 02/W/I02 .en
dc.format.extent051706-1en
dc.format.extent051706-11en
dc.format.mimetypeapplication/pdf
dc.language.isoenen
dc.relation.ispartofseriesPhysical Review Een
dc.relation.ispartofseries74en
dc.rightsYen
dc.subjectElectronic & Electrical Engineeringen
dc.titleExperimental demonstration, using polarized Raman and infrared spectroscopy that both conventional and de Vries smectic_A phase may exist in smectic liquid crystals with a first-order A-C* transitionen
dc.typeJournal Articleen
dc.contributor.sponsorScience Foundation Ireland (SFI)en
dc.type.supercollectionscholarly_publicationsen
dc.type.supercollectionrefereed_publicationsen
dc.identifier.peoplefinderurlhttp://people.tcd.ie/jvijen
dc.identifier.peoplefinderurlhttp://people.tcd.ie/atsuofen
dc.identifier.rssinternalid44770en
dc.identifier.doihttp://dx.doi.org/10.1103/PhysRevE.74.051706en
dc.identifier.rssurihttp://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=PLEEE8000074000005051706000001&idtype=cvips&prog=normalen


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