Molecular Crystals and Liquid Crystals, Vol.487, 39-51, 2008
Raman imaging of nematic and smectic liquid crystals
In this article, we demonstrate that confocal Raman microscopy can be utilized to image the director fields of liquid crystal molecules, revealing the spatial patterns of the molecular orientational order both in lateral and axial directions. Here we report on the polarized confocal Raman imaging of the electric field-aligned uniaxial nematic liquid crystal and the in-depth director profiling of the focal conic domains of smectic A liquid crystal. The C N stretching vibrational band [nu(CN)=2228cm(-1)] and the C-C stretch of aromatic rings [nu(CC)= 1606cm(-1)] are used to probe the spatial director orientations of 4-pentyl-4'-cyanobiphenyl (5CB) and 4-octyl-4'-cyanobiphenyl (8CB).
Keywords:confocal Raman microscopy;cyanobiphenyl liquid crystals;focal conic domains;orientational order;smectic A