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Optics Express

Optics Express

  • Editor: Michael Duncan
  • Vol. 14, Iss. 23 — Nov. 13, 2006
  • pp: 11433–11441

High-frequency dielectric relaxation of liquid crystals: THz time-domain spectroscopy of liquid crystal colloids

Masahito Oh-e, Hiroshi Yokoyama, Mattijs Koeberg, Euan Hendry, and Mischa Bonn  »View Author Affiliations


Optics Express, Vol. 14, Issue 23, pp. 11433-11441 (2006)
http://dx.doi.org/10.1364/OE.14.011433


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Abstract

Terahertz time-domain spectroscopy has been used to study the dielectric relaxation of pure 4’-n-pentyl-4-cyanobiphenyl (5CB) liquid crystal (LC) and its mixtures with 10 µm SiO2 particles in the frequency range 0.2–2 THz. For the pure sample, we find that spatial inhomogeneities consisting of oriented domains, comparable in size to our probe area (~1 mm2), cause a large scatter in the measured dielectric function, due to varying contributions from the ordinary and extraordinary components. In the LC/particle mixtures, ordering of the LC at the surface of the SiO2 particles results in a break-up of these domains, giving rise to a spatially much more homogeneous dielectric response. The inferred dielectric function can be interpreted using effective medium theory and the Debye relaxation model. We observe this stabilizing effect for interparticle distances < ~30 µm, setting a lower limit for the size of oriented domains in the bulk LC.

© 2006 Optical Society of America

OCIS Codes
(160.3710) Materials : Liquid crystals
(160.6030) Materials : Silica
(300.6250) Spectroscopy : Spectroscopy, condensed matter
(300.6270) Spectroscopy : Spectroscopy, far infrared
(320.7150) Ultrafast optics : Ultrafast spectroscopy

ToC Category:
Spectroscopy

History
Original Manuscript: September 1, 2006
Revised Manuscript: October 26, 2006
Manuscript Accepted: October 30, 2006
Published: November 13, 2006

Citation
Masahito Oh-e, Hiroshi Yokoyama, Mattijs Koeberg, Euan Hendry, and Mischa Bonn, "High-frequency dielectric relaxation of liquid crystals: THz time-domain spectroscopy of liquid crystal colloids," Opt. Express 14, 11433-11441 (2006)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-14-23-11433


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References

  1. W. B. Russel, D. H. Soville, and W. R. Schowalter, Colloidal Dispersions (Cambridge University Press, Cambridge, 1991).
  2. P. S. Drzaic, Liquid Crystal Dispersions, Series on Liquid Crystals (World Scientific, Singapore, 1995), Vol. 1.
  3. P. Poulin, H. Stark, T. C. Lubensky, and D. A. Weitz, "Novel Colloidal Interactions in Anisotropic Fluids, " Science 275, 1770-1773 (1997). [CrossRef] [PubMed]
  4. T. C. Lubensky, D. Pettey, N. Currier, and H. Stark, "Topological defects and interactions in nematic emulsions," Phys. Rev. E 57, 610 - 625 (1998). [CrossRef]
  5. P. Poulin and D. A. Weitz, "Inverted and multiple nematic emulsions," Phys. Rev. E 57, 626-637 (1998). [CrossRef]
  6. P. G. de Gennes and J. Prost, The Physics of Liquid Crystals (Oxford University Press, London, 1993).
  7. M. P. van Exter, Ch. Fattinger, D. Grischkowsky, "Terahertz time-domain spectroscopy of water vapor," Opt. Lett. 14, 1128 - 1130 (1989). [CrossRef]
  8. D. Grischkowsky, S. Keiding, M. P. van Exter, and Ch. Fattinger, "Far-infrared time-domain spectroscopy with terahertz beams of dielectrics and semiconductors," J. Opt. Soc. Am. B 7, 2006-2015 (1990). E. Knoesel, M. Bonn, J. Shan, and T. F. Heinz, "Charge transport and carrier dynamics in liquids probed by THz time-domain spectroscopy," Phys. Rev. Lett. 86, 340-343 (2001). [CrossRef]
  9. M. C. Beard, G. M. Turner, and C. A. Schmuttenmaer, "Terahertz Spectroscopy," J. Phys. Chem. B 106, 7146-7159 (2002); J. Shan, F. Wang, E. Knoesel, M. Bonn, and T. F. Heinz, "Measurement of the frequency-dependent conductivity in Sapphire," Phys. Rev. Lett. 90, 247401 (2003); E. Hendry, J. M. Schins, L. P. Candeias, L. D. A. Siebbeles, and M. Bonn, "Efficiency of exciton and charge carrier photogeneration in a semiconducting Polymer," Phys. Rev. Lett. 92, 196601 (2004); E. Hendry, F. Wang, J. Shan, T. F. Heinz, and M. Bonn, "Electron transport in TiO2 probed by THz time-domain spectroscopy," Phys. Rev. B 69, 081101 (2004). [CrossRef]
  10. C.-Y. Chen, T.-R. Tsai, C.-L. Pan, and R.-P. Pan, "Room temperature terahertz phase shifter based on magnetically controlled birefringence in liquid crystals," Appl. Phys. Lett. 83, 4497 - 4499 (2003). [CrossRef]
  11. T. Nose, S. Sato, K. Mizuno, J. Bae, and T. Nozokido, "Refractive index of nematic liquid crystals in the submillimeter wave region," Appl. Opt. 36, 6383-6387 (1997). [CrossRef]
  12. D. Turchinovich, P. Knobloch, G. Luessem, and M. Koch, "THz time-domain spectroscopy on 4-(trans-4’-pentylcyclohexyl)-benzonitril," in Liquid Crystals V, I.-C. Khoo, ed., Proc. SPIE 4463, 65-70 (2001). [CrossRef]
  13. T.-R. Tsai, C.-Y. Chen, C.-L. Pan, R.-P. Pan, and X.-C. Zhang, "Terahertz time-domain spectroscopy studies of the optical constants of the nematic liquid crystal 5CB," Appl. Opt. 42, 2372-2376 (2003). [CrossRef] [PubMed]
  14. C.-L. Pan, C.-F. Hsieh, R.-P. Pan, M. Tanaka, F. Miyamaru, M. Tani, and M. Hangyo, "Control of enhanced THz transmission through metallic hole arrays using nematic liquid crystal," Opt. Express 13, 3921-3930 (2005). [CrossRef] [PubMed]
  15. E. Hendry, PhD thesis Charge dynamics in novel semiconductors (University of Amsterdam, Netherlands, 2005).
  16. X. C. Zhang, Y. Jin, and X. F. Ma, "Coherent measurement of THz optical rectification from electro-optic crystals," Appl. Phys. Lett. 61, 2764-2766 (1992). [CrossRef]
  17. A. Nahata, A. S. Weling, and T. F. Heinz, "A wideband coherent terahertz spectroscopy system using optical rectification and electro-optic sampling," Appl. Phys. Lett. 69, 2321-2323 (1996). [CrossRef]
  18. P. C. M. Planken, H. K. Nienhuys, H. J. Bakker, and T. Wenckebach, J. Opt. Soc. Am. B 18, 313-317 (2001). [CrossRef]
  19. M. Born and E. Wolf, Principle of Optics, 6th ed., (Pergamon, Oxford, 1980).
  20. E. Hecht, Optics, 4th ed., (Benjamin Cummings, San Francisco, 2002).
  21. L. Duvillaret, F. Garet, and J. Coutaz, "A reliable method for extraction of material parameters in terahertz timedomain spectroscopy," IEEE J. Sel. Top. Quantum Electron. 2, 739 - 746 (1996). [CrossRef]
  22. C. A. Schmuttenmaer, "Exploring dynamics in the far-infrared with Terahertz Spectroscopy," Chem. Rev. 104, 1759 - 1779 (2004). [CrossRef] [PubMed]
  23. J. C. Maxwell-Garnett, Philos. Trans. R. Soc. London A203, 385 (1904). [CrossRef]
  24. A , Kirchner, K. Busch, and C. M. Soukoulis, "Transport properties of random arrays of dielectric cylinders," Phys. Rev. B 57, 277-288 (1998). [CrossRef]
  25. G. A. Niklasson, C. G. Granqvist, and O. Hunderi, "Effective medium models for the optical properties of inhomogeneous materials," Appl. Opt. 20, 26-30 (1981). [CrossRef] [PubMed]
  26. P. DebyePolar Molecules, (Dover, New York, 1929).
  27. M. Xu, P. Firman, S. Petrucci, and E. M. Eyring, "Molecular dynamics of organic carbonate solutions from 50 ps to 10 fs," J. Phys. Chem. 97, 3968-3973 (1993). [CrossRef]
  28. W. H. de Jue, Physical Properties of Liquid Crystalline Materials (Gordon and Breach, Science Publishers Inc., New York, 1980).
  29. B. R. Ratna and R. Shashidhar, "Dielectric properties of 4’-n-alkyl-4-cyanobiphenyls in their nematic phases," Pramana 6, 278-283 (1976). [CrossRef]
  30. D. Lippens, J. P. Parneix, and A. Chapoton, "Etude du 4 heptyl 4’ cyanobiphenyl a partir de l’analyse de ses proprietes dielectriques," J. de Physique 38, 1465-1471 (1977). [CrossRef]
  31. S.-T. Wu, C.-S. Wu, M. Warenghhem, and M. Ismaili, Opt. Eng. 32, 1775-1780 (1993). [CrossRef]
  32. G. P. Sinha and F. M. Aliev, "Dielectric spectroscopy of liquid crystals in smectic, nematic, and isotropic phases confined in random porous media," Phys. Rev. E 58, 2001-2010 (1998). [CrossRef]
  33. J. Leys, G. Sinha, C. Glorieux, and J. Thoen, "Influence of nanosized confinements on 4-n-decyl-4’- cyanobiphenyl (10CB): A broadband dielectric study," Phys. Rev. E 71, 051709 (2005). [CrossRef]

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