Critical slowing down of fluctuations in p-terphenyl and p-quaterphenyl observed by proton spin-lattice relaxation |
| |
Authors: | B Toudic J Gallier P Rivet H Cailleau |
| |
Institution: | Groupe de Physique Cristalline, ERA au CNRS No. 070015, Université de Rennes I, Campus de Beaulieu, 35042 Rennes-Cedex, France |
| |
Abstract: | The temperature evolution of the proton spin-lattice relaxation time T1 in p-terphenyl and in p-quaterphenyl around their order-disorder phase transition has been measured. In both cases pretransitional collective fluctuations destroy the high temperature Arrhenius behaviour of the relaxation rate corresponding to a single reorientational jump motion. The spin-lattice relaxation times present then a drastic decrease until the transition temperature (T0 = 193 K in p-terphenyl, T0 = 238 K in p-quaterphenyl). This decrease is associated to the critical slowing down of fluctuations. In the low temperature phase the ordering phenomena lead to a sharp drop of the spin-lattice relaxation rate. |
| |
Keywords: | |
本文献已被 ScienceDirect 等数据库收录! |