Study of chiral molecular diffusion in anisotropic liquids
Karen Allahverdyan and Tigran Galstian
Center for Optics, Photonics and Laser (COPL),Department of Physics, Engineering Physics and Optics, Laval University,Pav. d’Optique-Photonique, 2375 Rue de la Terrasse, Québec, Canada G1V 0A6
Presented by: K. [email protected]
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Chirality
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The presence of chiral compound in liquids
Reflective LC displays, thermometers (temperature distribution maps), circular polarizers, dichroic filters& mirrors… Smart windows…
Photonic band gap structures
Optical activity • Manipulation of light polarization & path• Precise measurement of concentration • Various biomedical applications, drugs …• etc.
In isotropic liquids
Periodic structure• 1D photonic crystal• Tunable Bragg gratings• Selective reflection• Etc.
In anisotropic liquids
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Chiral compound in anisotropic liquids
NLC CLC
Chiral dopant
Boundary conditionsStrong
rubbing
Chiral dopant
Weak
Chiral dopant
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Chiral droplet in NLC
Strong boundary conditions vs Weak boundary conditions
For given materials, the temperature is the major factor acting on the diffusion dynamics.
𝑣 1𝑘𝑇
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15min
Chiral droplet in NLC10h
0.5mm
18h
Rubbed(strong)
Non-rubbed(weak)
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r
d
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The evolution of fringes
0 5 100102030405060708090100110120
Weak
d(um
)
Time (hour)
Strong
0 2 4 6 8 10 12
100
200
300
400
500
Weak
r (um
)
Time (hour)
Strong
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Azobenzene droplet in NLC
0.5mm
Rubbed(strong)
Non-rubbed(weak)
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The diffusion dynamics
-200 -100 0 100 2000
20
40
60
80
100
120
140
160
20h
4h
15min
Distance (a.u.)
Blue
from
RG
B
Distribution of azo. concentration
The diffusion processes are similar in both cases (strong or weak boundaries)
The diffusion is faster in the rubbing direction.
0 50 100 150 200 250 3000
5
10
15
20
25
30
35
Weak
Strong(parallel)
Diffu
sion
dep
th (a
.u)
Time (min)
Strong(perp.)
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Agglomeration of chiral molecules
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• The diffusion of chiral molecules in anisotropic liquids is different then in isotropic liquids.
• The boundary conditions can be used to control the diffusion dynamics in anisotropic liquids.
• The differences and the possibility of control is due to collective organizing tendency of liquid crystals.
Conclusion
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