| Autor: |
Chilaya, G. S., Elashvili, Z. M., Lisetski, L. N., Piliashvili, T. S., Vinokur, K. D. |
| Zdroj: |
Molecular Crystals and Liquid Crystals; September 1981, Vol. 74 Issue: 1 p261-273, 13p |
| Abstrakt: |
Temperature dependences of the helical pitch have been studied for different induced cholesteric systems. It is shown that the sign of dP/dT in the same nematic solvent, may depend upon the nature of optically active dopants. For example, typical non-smectogenic nematics exhibit dP/dT values which are positive with l-menthol derivatives, and negative if the induced chirality is due to tygogenyn derivatives. A general theory of cholesteric pitch is developed providing an explanation of the experimental data in question as well as a description of pitch vs. concentration relationships in nematic - cholesteric mixtures. Also presented are some data for induced cholesteric systems with a smectogenic nematic component, where pretransitional phenomena with P → ∞ are observed. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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