Anisotropic Ultrasonic Properties of a Nematic Liquid Crystal

Abstract

Ultrasonic measurements (2 to 6 MHz) on a room-temperature nematic liquid crystal have shown the attenuation to vary strongly with the angle 6 between the sound-wave propagation direction and the direction of an aligning magnetic field. The velocity change is quite small, amounting to some 0.1 % between the 9 = 90° and the 0 = 0° case. The orientation-dependent attenuation is of the hysteresis type.

Coherence Length in the Isotropic Phase of a Room-Temperature Nematic Liquid Crystal

“…Dielectric and resistivity anisotropy, 1,2 and anisotropic ultrasonic properties 3 of MBBA have been reported. Jones, Creagh, and Lu 4 ' 5 have studied the dynamic scattering 6 characteristics of MBBA, while Litster and his co-workers have investigated the intensity and spectrum of scattered light in the nematic 7 as well as the isotropic phase.…”

Anisotropic Ultrasonic Properties of a Smectic Liquid Crystal

“…6 The experimental situation has already been described in an earlier publication. 7 unit supplied an electrical pulse to the input quartz crystal. The voltage picked up by the output quartz crystal was amplified and then fed into the receiver portion of the MATEC unit.…”

Dispersion and absorption of sound in nematics

“…To compare these results with experimental results for MBBA we fitted A e(f)/f2, measured by Lord and Labes [7] and by Wetsel, Speer, Lowry, and Woodard [8], and thus determined the parameters AE~, AEs, ~, and z5. These values we used to calculate the anisotropy of the sound velocity as measured by Mullen, Liithi, and Stephen [10].…”

“…The experimental data on ultrasonic absorption in MBBA [7][8][9] are used to fit the values of the elastic constants and the relaxation * For our purpose, the determination of eigenmodes, it is not necessary to take account of the limitations [5] of Rytov's work. times involved.…”