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Chirality Detection Using Nematic Liquid Crystal Droplets on Anisotropic Surfaces

Per Rudquist (Institutionen för mikroteknologi och nanovetenskap, Fotonik) ; C. F. Dietrich ; A. G. Mark ; F. Giesselmann
Langmuir (0743-7463). Vol. 32 (2016), 24, p. 6140-6147.
[Artikel, refereegranskad vetenskaplig]

Nematic liquid crystals (NLCs) form helical macroscopic structures through chiral induction when doped with chiral species. We describe a very simple, though highly sensitive method for determination of handedness and pitch of the induced twist in the case of very weak twisting powers of such chiral dopants. A tiny drop typically less than 10 nL-of the chiral doped NLC is placed on a plate promoting a uniform planar surface anchoring of the liquid crystal director. At the curved NLC air interface the anchoring is homeotropic and in the sessile droplets we get a locally twisted hybrid director structure with a disclination line extending across the droplet. The configuration of the disclination line (S-like or backwards S-like) reveals the sign of twisting power and extremely large pitch values in the range of 10 mm can easily be measured. We demonstrate the method using the standard NLC 4-cyano-4'-pentylbiphenyl (5CB), weakly doped with the chiral material 2-hydroxy-2-phenylacetic acid (mandelic acid).

Nyckelord: helical twisting power, molecular chirality, cholesteric pitch, phases, configuration, polarization, model, index, cell, Chemistry, Materials Science, egemeyer h, 1987, berichte der bunsen-gesellschaft-physical chemistry chemical physics, v91, p3, raley jp, 1974, physical review a, v10, p1881, egemey.h, 1971, naturwissenschaften, v58, p599

Denna post skapades 2016-08-17.
CPL Pubid: 240352


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Institutionen för mikroteknologi och nanovetenskap, Fotonik



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