MONITORING ULTRASLOW MOTIONS IN ORGANISED LIQUIDS NMR Experiments and computer simulations

摘要

The interest to liquid crystals confined in porous materials has greatly increased in recent years due to their important applications in new electro-optic technologies Confinements by pores and surface interactions produce strong effects on the properties of liquid crystalline systems both below and above the bulk clearing point. The aim of this work is the study of a surface induced orientational anisotropy of constrained liquid crystals above the nematic-isotropic transition temperature on the basis of the stimulated echo experiments and the computer simulations. Surface effects are strongest in the near vicinity of the wall. In this work our attention will be focused on the materials with pore sizes of a few nanometer much less studied than the materials with relatively big pores. In liquids, the modulations of dipolar interaction by stochastic molecular motions determine the most important mechanisms of relaxation. We present the computer simulations of random walks constrained by uneven surface aiming at a numerical evaluation of the correlation function of spherical harmonics proportional to a reduced dipolar auto-correlation function.