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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 18, Iss. 6 — Mar. 15, 2010
  • pp: 6097–6107

Molecular properties of liquid crystals in the terahertz frequency range

Nico Vieweg, Christian Jansen, Mohammad Khaled Shakfa, Maik Scheller, Norman Krumbholz, Rafal Wilk, Martin Mikulics, and Martin Koch  »View Author Affiliations

Optics Express, Vol. 18, Issue 6, pp. 6097-6107 (2010)

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We report on a first experimental study of the molecular properties of nematic liquid crystals in the terahertz range. In the beginning, we extract the frequency and temperature dependent refractive index and absorption coefficient of the cyanobiphenyls 5CB, 6CB and 7CB from terahertz time domain spectroscopy measurements and investigate the impact of the alkyl chain length on the macroscopic liquid crystal characteristics, focusing especially on the pronounced odd and even effect. Next, we deduce the principle polarizabilities and the order parameter S by applying Vuks’ approximation and Haller’s approach. On this basis, we calculate the main polarizabilities along the longitudinal and transverse axis and link the observed terahertz properties to the molecular structure of the liquid crystals.

© 2010 Optical Society of America

OCIS Codes
(160.3710) Materials : Liquid crystals
(300.6495) Spectroscopy : Spectroscopy, teraherz

ToC Category:

Original Manuscript: January 5, 2010
Revised Manuscript: March 9, 2010
Manuscript Accepted: March 9, 2010
Published: March 11, 2010

Nico Vieweg, Christian Jansen, Mohammad Khaled Shakfa, Maik Scheller, Norman Krumbholz, Rafal Wilk, Martin Mikulics, and Martin Koch, "Molecular properties of liquid crystals in the terahertz frequency range," Opt. Express 18, 6097-6107 (2010)

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  1. F. Reinitzer, "Beiträge zur Kenntniss des Cholesterins," Monatsh. Chem. 9(1), 421-441 (1888). [CrossRef]
  2. O. Lehmann, "Über fliessende Krystalle," Z. Phys. Chem. 4, 462-472 (1889).
  3. M. Schadt and W. Helfrich, "Voltage-Dependent Optical Activity of a Twisted Nematic Liquid Crystal," Appl. Phys. Lett. 18(4), 127-128 (1971). [CrossRef]
  4. R. S. McEwen, "Instrument Science and Technology," J. Phys. E Sci. Instrum. 20(4), 364-377 (1987). [CrossRef]
  5. E. P. Raynes and I. A. Shanks, "Fast-Switching Twisted Nematic Electro-Optical Shutter and Colour Filter," Electron. Lett. 10(7), 114-115 (1974). [CrossRef]
  6. 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(25), 6383-6387 (1997). [CrossRef]
  7. D. Turchinovich, P. Knobloch, G. Luessem, and M. Koch, "THz time-domain spectroscopy on 4-(trans-4-pentylcyclohexyl)-benzonitril," Proc. SPIE 4463, 65-70 (2001). [CrossRef]
  8. R. P. Pan, C. F. Hsieh, C. L. Pan, and C. Y. Chen, "Temperature-dependent optical constants and birefringence of nematic liquid crystal 5CB in the terahertz frequency range," J. Appl. Phys. 103(9), 093523 (2008). [CrossRef]
  9. K. C. Lim, J. D. Margerum, A. M. Lackner, L. J. Miller, E. Sherman, and W. H. Smith, Jr., "Liquid crystal birefringence for millimeter wave radar," Liq. Cryst. 14(2), 327-337 (1993). [CrossRef]
  10. H. Fujikake, T. Kuki, H. Kamoda, F. Sato, and T. Nomoto, "Voltage-variable microwave delay line using ferroelectric liquid crystal with aligned submicron polymer fibers," Appl. Phys. Lett. 83(9), 1815-1817 (2003). [CrossRef]
  11. F. Yang and J. R. Sambles, "Microwave liquid-crystal variable phase grating," Appl. Phys. Lett. 85(11), 2041-2043 (2004). [CrossRef]
  12. C. Y. Chen, C. L. Pan, C. F. Hsieh, Y. F. Lin, and R. P. Pan, "Liquid-crystal-based terahertz tunable Lyot filter," Appl. Phys. Lett. 88(10), 101107 (2006). [CrossRef]
  13. Z. Ghattan, T. Hasek, R. Wilk, M. Shahabadi, and M. Koch, "Sub-terahertz on-off switch based on a twodimensional photonic crystal infiltrated by liquid crystals," Opt. Commun. 281(18), 4623-4625 (2008). [CrossRef]
  14. R. Wilk, N. Vieweg, O. Kopschinski, and M. Koch, "Liquid crystal based electrically switchable Bragg structure for THz waves," Opt. Express 17(9), 7377-7382 (2009). [CrossRef] [PubMed]
  15. G. W. Gray, K. J. Harrison, and J. A. Nash, "New Family of Nematic Liquid Crystals for Displays," Electron. Lett. 9(6), 130-131 (1973). [CrossRef]
  16. R. Wilk, N. Vieweg, O. Kopschinski, T. Hasek, and M. Koch, "THz Spectroscopy of Liquid Crystals from the CB family," J Infrared Milli Terahz Waves 30(11), 1139-1147 (2009). [CrossRef]
  17. R. G. Horn, "Refractive indices and order parameters of two liquid crystals," J. Phys. 39, 105-109 (1978). [CrossRef]
  18. N. C. Shivaprakash, M. M. M. Abdoh, S. Prasad, and J. S. Prasad, "Refractive indices, densities, polarizabilities and molecular order in cholesteric liquid crystals," Mol. Cryst. Liq. Cryst.  80(1), 179-193 (1982). [CrossRef]
  19. Y. N. Murthy and V. R. Murthy, "Molecular Polarizabilities, Polarizability Anisotropies and Order Parameters of Nematic Liquid Crystals," Cryst. Res. Technol. 32(7), 999-1005 (1997). [CrossRef]
  20. D. Dunmur and K. Toriyama, in Physical Properties of Liquid Crystals, edited by D. Demus, J. Goodby, G.W. Gray, H.-W. Spiess, and V. Vill (Wily-VCH, Wernheim 1999).
  21. V. Vill, Liquid Crystal Database 4.6, LCI Publisher (2005), https://liqcryst.chemie.uni-hamburg.de.
  22. M. I. Capar and E. Cebe, "Molecular dynamic study of the odd-even effect in some 4-n-alkyl-4′-cyanobiphenyls," Phys. Rev. E Stat. Nonlin. Soft Matter Phys. 73(6), 061711 (2006). [CrossRef] [PubMed]
  23. S. Marčelja, "Chain ordering in liquid crystals. I. Even-odd effect," J. Chem. Phys. 60(9), 3599-3604 (1974). [CrossRef]
  24. J. R. Lalanne, J. C. Rayez, B. Duguay, A. Proutiere, and R. Viani, "Molecular aspect of the even-odd effect in cyanobiphenyls (nCB): Theoretical studies of the molecular geometrical conformation and optical anisotropy," J. Chem. Phys. 81(1), 344-348 (1984). [CrossRef]
  25. I. Chirtoc, M. Chirtoc, C. Glorieux, and J. Thoen, "Determination of the order parameter and its critical exponent for nCB (n=5-8) liquid crystals from refractive index data," Liq. Cryst. 31(2), 229-240 (2004). [CrossRef]
  26. P. U. Jepsen, R. H. Jacobsen, and S. R. Keiding, "Generation and detection of terahertz pulses from biased semiconductor antennas," J. Opt. Soc. Am. B 13(11), 2424-2436 (1996). [CrossRef]
  27. N. Vieweg, M. Mikulics, M. Scheller, K. Ezdi, R. Wilk, H. W. Hübers, and M. Koch, "Impact of the contact metallization on the performance of photoconductive THz antennas," Opt. Express 16(24), 19695-19705 (2008). [CrossRef] [PubMed]
  28. R. Wilk, I. Pupeza, R. Cernat, and M. Koch, "Highly accurate THz time-domain spectroscopy of multi-layer structures," IEEE J. Sel. Top. Quantum Electron. 14(2), 392-398 (2008). [CrossRef]
  29. M. Scheller, C. Jansen, and M. Koch, "Analyzing sub-100-μm samples with transmission terahertz time domain spectroscopy," Opt. Commun. 282(7), 1304-1306 (2009). [CrossRef]
  30. S. T. Wu, "Birefringence dispersions of liquid crystals," Phys. Rev. A 33(2), 1270-1274 (1986). [CrossRef] [PubMed]
  31. S. T. Wu, "Absorption measurements of liquid crystals in the ultraviolet, visible, and infrared," J. Appl. Phys. 84(8), 4462-4465 (1998). [CrossRef]
  32. J. Li, and S. T. Wu, "Extended Cauchy equations for the refractive indices of liquid crystals," J. Appl. Phys. 95(3), 896-901 (2004). [CrossRef]
  33. J. Li, S. Gauza, and S. T. Wu, "Temperature effect on liquid crystal refractive indices," J. Appl. Phys. 96(1), 19-24 (2004). [CrossRef]
  34. M. Evans, M. Davis, and I. Larkin, "Molecular Motion and Molecular Interaction in the Nematic and Isotropic Phases of a Liquid Crystal Compound," J. C. S. Faraday II 69, 1011-1022 (1973). [CrossRef]
  35. M. F. Vuks, "Determination of the Optical Anisotropy of Aromatic Molecules from the Double Refraction of Crystals," Opt. Spektrosk. 20, 644-651 (1966).
  36. I. Haller, "Thermodynamic and static properties of liquid crystals," Solid-State Chemistry 10, 103-118 (1975). [CrossRef]
  37. S. Chandrasekhar, and N. V. Madhusudana, "Orientational Order in p-Azoxyanisole, p-Azoxyphenetole and their mixtures in the nematic phase," J. Phys. Colloq. 30(C4), C4-24 (1969). [CrossRef]
  38. C. J. F. Böttcher, Theory of Electric Polarisation, (Elsevier Publishing Company, Amsterdam, Houston, London, New York 1952).
  39. Landolt-Börnstein, Group VIII Advanced Materials and Technologies, Physical Properties of Liquid Crystals, (Springer, 2003.) Vol. 5A p. 12.
  40. W. Maier, and A. Saupe, Z. Naturforsch. B 14a, 882 (1959).
  41. G. Heppke, and C. Bahr, " Flüssigkristalle," Bergmann/Schaefer, Lehrbuch der Experimentalphysik, Band V.,(de Gruyter, Berlin, p. 389-445, 1992).
  42. P. J. Collings, and M. Hird, in Introduction to Liquid Crystals Chemistry and Physics, G. W. Gray, J.W. Goodby, and A. Fukuda, ed.(Taylor & Francis, London, 2004).
  43. S. Urban, A. Würflinger, and B. Gestblom, "On the derivation of the nematic order parameter from the dielectric relaxation times," Phys. Chem. Chem. Phys. 1(11), 2787-2791 (1999). [CrossRef]
  44. A. Buka and W. de Jeu, "Diamagnetism and orientational order of nematic liquid crystals," J. Phys. 43, 361-367 (1982). [CrossRef]
  45. J. A. Ratto, S. Ristori, F. Volino, M. Pineri, M. Thomas, M. Escoubes, and R. B. Blumstein, "Investigation of a liquid crystal dispersed in an ionic polymeric membrane," Chem. Mater. 5(10), 1570-1576 (1993). [CrossRef]
  46. I. H. Ibrahim and W. Haase, "On the Molecular Polarizability of Nematic Liquid Crystals," Mol. Cryst. Liq. Cryst. 66(1), 189-198 (1981). [CrossRef]

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