Light-Scattering Studies of Liquid Crystals

Application of field-cycling NMR relaxometry to the study of ultrasound-induced effects in the molecular dynamics and order of mesomorphic materials

“…For an ideal smectic A phase, twist and bend elastic distortions are forbidden [19]. For an undistorted smectic, only the splay term of the nematic elastic free energy survives ( f n ).…”

“…The order parameter for the smectic A phase is defined as the amplitude of a one-dimensional density wave whose wave vector points along the director [16,19]: (2) where |Ψ | is a measure of the strength of the smectic order, ρ 0 is the average density, q 0 = 2π /d is the wave vector of the density wave (being d the interlayer distance), ϕ is an arbitrary phase, and z is the coordinate perpendicular to the planes.…”

Optical determination of viscoelastic properties of nematic OHMBBA

“…Introduction. -Light scattered by local director fluctuations of an aligned nematic liquid crystal (NLC) yields information about the viscoelastic properties of that crystal [1,2,3]. In this paper we describe light scattering experiments on OHMBBA, which produce data about the splay/twist elastic ratio and the splay and the twist viscoelastic ratios.…”