ESR Study of Molecular Ordering in PEBAB and PMBAB

1984 ◽  
Vol 39 (7) ◽  
pp. 700-702 ◽  
Author(s):  
N. V. S. Rao ◽  
V. G. K. M. Pisipati ◽  
P. V. Datta Prasad ◽  
D. Saran
Keyword(s):  
Liquid Crystals ◽  
Order Parameter ◽  
Close Agreement ◽  
Nematic Liquid Crystals ◽  
Nitroxide Radical ◽  
Molecular Ordering ◽  
Paramagnetic Probe

An ESR study of the nematic liquid crystals PEBAB and PMBAB has been carried out using a nitroxide radical as paramagnetic probe. The order parameter (5) determined this way are in close agreement with those determined by NMR. For EBAB our S values differ from those determined by ESR with a different probe (VAAC).

ESR Study of Molecular Ordering in 50.1,50.2 and 50.4

1985 ◽  
Vol 40 (5) ◽  
pp. 469-471
Author(s):  
N. V. S. Rao ◽  
V. G. K. M. Pisipati ◽  
P. V. Datta Prasad ◽  
D. Saran
Keyword(s):  
Liquid Crystals ◽  
Close Agreement ◽  
Nitroxide Radical ◽  
Order Parameters ◽  
Refractive Indices ◽  
Molecular Ordering ◽  
Paramagnetic Probe

An ESR study of the liquid crystals N(p-n-pentyloxy benzylidene) p-n-alkylanilines [alkyl = methyl, 50.1; ethyl, 50.2; butyl, 50.4] has been carried out using a nitroxide radical as paramagnetic probe. The order parameters determined in this way are in close agreement with those determined from refractive indices by the Neugebauer method.

Molecular Ordering in Nematic MBCA and EPAPU

1990 ◽  
Vol 45 (1) ◽  
pp. 29-32
Author(s):  
S. Sreehari Sastry ◽  
V. Venkata Rao ◽  
P. Narayana Murty ◽  
G. Satyanandam ◽  
T. F. Sundar Raj
Keyword(s):  
Phase Transition ◽  
Liquid Crystals ◽  
Order Parameter ◽  
Nematic Phase ◽  
Spin Probe ◽  
Nematic Liquid Crystals ◽  
Experimental Techniques ◽  
First Order ◽  
Molecular Ordering

AbstractBy EPR, two nematic liquid crystals (MBCA and EPAPU) were investigated using a steroidal nitroxide spin probe. In both liquid crystals the isotropic-nematic phase transition is of first order. The observed variation of the order parameter with temperature is compared with predictions from the Maier-Saupe and Humphries-James-Luckhurst models and with results obtained by several other experimental techniques.

Order parameter of dual-frequency nematic liquid crystals measured over a wide range of thicknesses

2020 ◽  
Vol 47 (9) ◽  
pp. 1338-1344
Author(s):  
Olha Melnyk ◽  
Yuriy Garbovskiy ◽  
Anatoliy Glushchenko
Keyword(s):  
Liquid Crystals ◽  
Order Parameter ◽  
Nematic Liquid Crystals ◽  
Dual Frequency ◽  
Wide Range

Effects of Conjugation of Mesogenic Core of Nematic Liquid Crystals for Polar Anchoring Energy and Surface Order Parameter on Rubbed Polyimide Films

1994 ◽  
Vol 33 (Part 2, No. 8B) ◽  
pp. L1174-L1177 ◽  
Author(s):  
Dae-Shik Seo ◽  
Norihiro Yoshida ◽  
Shunsuke Kobayashi ◽  
Michinori Nishikawa ◽  
Yoshikazu Yabe
Keyword(s):  
Liquid Crystals ◽  
Order Parameter ◽  
Nematic Liquid Crystals ◽  
Polyimide Films ◽  
Anchoring Energy

scholarly journals Dynamic Grating Recording by a Light-Induced Modification of the Order Parameter in Dye-Doped Chiral Nematic Liquid Crystals

2019 ◽  
Vol 64 (4) ◽  
pp. 293 ◽  
Author(s):  
A. Iljin ◽  
D. Wei ◽  
U. Bortolozzo ◽  
S. Residori
Keyword(s):  
Liquid Crystals ◽  
Order Parameter ◽  
Response Times ◽  
Nematic Liquid Crystals ◽  
Helical Structure ◽  
Fast Response ◽  
Optical Nonlinearity ◽  
Chiral Structure ◽  
Chiral Nematic ◽  
Dynamic Grating

The dynamic grating recording in dye-doped chiral nematic liquid crystals is studied. It is shown that the mechanism responsible for the grating recording can be ascribed to a photoinduced modification of the order parameter of a liquid crystal within the range of optical intensities, for which the orientational nonlinearity remains quenched by the structural order of the chiral structure. The two-wave mixing dynamic behavior is analyzed for different intensities of the recording beams, by comparing the self-diffraction regime with the probe diffraction. This allows us to distinguish a particular mechanism of optical nonlinearity. The photo-induced modulation of the order parameter and the respective changes of medium’s refractive indices determine the relatively fast response times, local nonlinear response, and quite high diffraction efficiency within an extremely wide intensity range (more than three orders of magnitude) The chiral helical structure hinders the nematic director reorientation, prevents the appearance of surface effects, and is very favorable for the manipulation of a nonlinear polarization. Such new mechanism could also be extended to the recording of arbitrary phase profiles as requested in several applications for the manipulation of a light-beam.

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