Reorientational motion and volumetric behavior in the binary mixtures of 4-cyano-4′-pentylbiphenyl and triphenylphosphite

Matsuoka, Tatsuro; Mizoguchi, Yasunori; Koda, Shinobu; Onoda-Yamamuro, Noriko; Ogawa, Hideo; Nomura, Hiroyasu

doi:10.1016/j.molliq.2004.10.016

Cited by 2 publications

(1 citation statement)

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“…A translational− rotational mode coupling was also found in highly anisotropic molecular systems as phenyl-salicylate (Salol), 31,32 as well as in the Iso phase of the liquid crystals p-methoxybenzylidene-nbutylaniline (MBBA), triphenylphosphite (TPP), 4′-pentyl-4cyanobiphenyl (5CB), and their mixtures. 33,34 It explains why, in the Iso phase, high frequency dispersions merge into a single branch rather than splitting as in the SmA phase. Therefore, the merging of the dispersion curves at intermediate and high Qs leads to a shift of the longitudinal branch toward higher energies (phononic hardening, see Figure 3c) than in the Cryst or SmA phases.…”

Section: Nano Lettersmentioning

confidence: 99%

Emergent Optical Phononic Modes upon Nanoscale Mesogenic Phase Transitions

et al. 2017

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The investigation of phononic collective excitations in soft matter systems at the molecular scale has always been challenging due to limitations of experimental techniques in resolving low-energy modes. Recent advances in inelastic X-ray scattering (IXS) enabled the study of such systems with unprecedented spectral contrast at meV excitation energies. In particular, it has become possible to shed light on the low-energy collective motions in materials whose morphology and phase behavior can easily be manipulated, such as mesogenic systems. The understanding of collective mode behavior with a Q-dependence is the key to implement heat management based on the control of a sample structure. The latter has great potential for a large number of energy-inspired innovations. As a first step toward this goal, we carried out high contrast IXS measurements on a liquid crystal sample, D7AOB, which exhibits solid-like dynamic features, such as the coexistence of longitudinal and transverse phononic modes. For the first time, we found that these terahertz phononic excitations persist in the crystal, smectic A, and isotropic phases. Furthermore, the intermediate smectic A phase is shown to support a van der Waals-mediated nonhydrodynamic mode with an optical-like phononic behavior. The tunability of the collective excitations at nanometer-terahertz scales via selection of the sample mesogenic phase represents a new opportunity to manipulate optomechanical properties of soft metamaterials.

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Section: Nano Lettersmentioning

confidence: 99%