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'Proton Relaxation' in keywords Facet   Publication Year 1996  [X]
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1Author    C. Cruz, J. L. Figueirinhas, P. J. Sebastião, A. C. Ribeiro, F. Noack, H. T. Nguyen, B. Heinrich, D. Guillon, I.P C MRequires cookie*
 Title    Molecular Dynamics in the Columnar and Lamellar Mesophases of a Liquid Crystal of Biforked Molecules  
 Abstract    In this work we present the first study of molecular dynamics in the S c and 4> h mesophases of a liquid crystal of biforked molecules. This study was performed by means of proton NMR relaxation measurements obtained at different temperatures in the studied phases, combining standard and fast field-cycling techniques in order to cover a large domain of Larmor frequencies (100 Hz-300 MHz). The experimental results were analysed considering the potential contributions of different relax-ation mechanisms, namely local molecular rotational reorientations, self-diffusion and collective movements. The description of the contributions of the rotational reorientations and self-diffusion mechanisms are not quite different in the two studied phases. The main distinction in the molecular dynamics is found in the low Larmor frequency range dominated by the collective movements. While in the S c phase this contribution can be described by the law characteristic of smectic layer undulations, the contribution of the collective movements in the </> h phase can be assigned to elastic deformation of the columns. 
  Reference    Z. Naturforsch. 51a, 155—166 (1996); received November 29 1995 
  Published    1996 
  Keywords    NMR, Proton Relaxation, Molecular Dynamics, Biforked Molecules, </> h Mesophase 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0155.pdf 
 Identifier    ZNA-1996-51a-0155 
 Volume    51