Langmuir-Blodgett films: molecular engineering of non-centrosymmetric structures for second-order nonlinear optical applications

Abstract

Optical second-harmonic generation (SHG) is conditional upon the structure being non-centrosymmetric and consequently, the Langmuir-Blodgett (LB) technique is of interest because it permits control at the molecular level. However, the criteria for alignment at the air/water interface, >i.e. a hydrophilic head and a hydrophobic tail, tend to impede the required packing arrangement within the multilayer. Most show inversion symmetry with the interfaces being alternately hydrophobic (tail-to-tail) and hydrophilic (head-to-head). This has been overcome by interleaving the layers with inactive spacers and, in such films, the long-range structural order is controlled by utilising compatible component molecules, interdigitating arrangements (‘molecular zips’) and interlayer hydrogen-bonding. Furthermore, the employment of optically nonlinear chromophores with two hydrophobic end groups eliminates the need for inactive spacers. The molecules form stable non-centrosymmetric structures because, unlike above, the interfaces are invariably hydrophobic. In this review, the molecular requirements for LB deposition are discussed together with the film-forming behaviour and properties of a variety of optically nonlinear materials.

References

1. (a) Nonlinear Optical Properties of Organic Molecules and Crystals, ed. D. S. Chemla and J. Zyss, Academic Press, Orlando, 1987; (b) P. N. Prasad and D. J. Williams, Introduction to Nonlinear Optical Effects in Molecules and Polymers, John Wiley & Sons, New York, 1991; (c) Optical Nonlinearities in Chemistry, ed. J. Michl, Chem. Rev., 94, 1994; (d) C. Bosshard, K. Sutter, P. Pretre, J. Hulliger, M. Flörsheimer, P. Kaatz and P. Günter, Organic Nonlinear Optical Materials, Gordon and Breach, Basel, 1995.
2. G. J. Ashwell, G. Jefferies, D. G. Hamilton, D. E. Lynch, M. P. S. Roberts, G. S. Bahra and C. R. Brown, Nature, 1995, 375, 385.
3. G. J. Ashwell, M. P. S. Roberts, N. D. Rees, G. S. Bahra and C. R. Brown, Langmuir, 1998, 14, 5279.
4. A. Dulcic, C. Flytzanis, C. L. Tang, D. Pépin, M. Fétizon and Y. Hoppilliard, J. Chem. Phys., 1981, 74, 1559.
5. R. A. Huijts and G. L. J. Hesselink, Chem. Phys. Lett., 1989, 156, 209.
6. I. Ledoux, J. Zyss, A. Jutand and C. Amatore, Chem. Phys., 1991, 150, 177.
7. A. Dulcic and C. Sauteret, J. Chem. Phys., 1978, 69, 3453.
8. S. R. Marder, D. N. Beratan and L.-T. Cheng, Science, 1991, 252, 103.
9. D. J. Williams, Angew. Chem., Int. Ed. Engl., 1984, 23, 690.
10. S. R. Marder and J. W. Perry, Adv. Mater., 1993, 5, 804.
11. J. F. Nicoud and R. J. Twieg, in Nonlinear Optical Properties of Organic Molecules and Crystals, ed. D. S. Chemla and J. Zyss, Academic Press, Orlando, 1987.
12. K. D. Singer, S. L. Lalama, J. E. Sohn and R. D. Small, in Nonlinear Optical Properties of Organic Molecules and Crystals, ed. D. S. Chemla and J. Zyss, Academic Press, Orlando, 1987.
13. (a) G. Decher, B. Tieke, C. Bosshard and P. Günter, J. Chem. Soc., Chem. Commun., 1988, 933; (b) C. Bosshard, G. Decher, B. Tieke and P. Günter, Proc. SPIE-Int. Soc. Opt. Eng., 1988, 1017, 141.
14. (a) Q. Tang, S. A. Zahir, C. Bosshard, M. Flörsheimer, M. Küpfer and P. Günter, Thin Solid Films, 1992, 210–211, 195; (b) M. Küpfer, M. Flörsheimer, W. Baumann, C. Bosshard and P. Günter, Spec. Publ. R. Soc. Chem., 1993, 137, 74.
15. G. Decher, B. Tieke, C. Bosshard and P. Günter, Ferroelectrics, 1989, 91, 193.
16. V. A. Howarth, N. Asai, N. Kishi and I. Fujiwara, Appl. Phys. Lett., 1992, 61, 1616.
17. (a) Y. Miyamoto, K. Kaifu, T. Koyano, M. Saito and M. Kato, Jpn. J. Appl. Phys., 1991, 30, L1647; (b) K. Kaifu, Y. Miyamoto, M. Saito and K. Masakazu, J. Photopolym. Sci. Technol., 1993, 6, 189.
18. (a) W. M. K. P. Wijekoon, B. Asgharian, P. N. Prasad, T. Geisler and S. Rosenkilde, Thin Solid Films, 1992, 208, 137; (b) T. Geisler, S. Rosenkilde, P. S. Ramanujam, W. M. K. P. Wijekoon and P. N. Prasad, Phys. Scr., 1992, 46, 127.
19. (a) H. Nakahara, W. Liang, H. Kimura, T. Wada and H. Sasabe, J. Opt. Soc. Am. B, 1998, 15, 458; (b) W. Liang, H. Nakahara, H. Kimura, T. Wada and H. Sasabe, Thin Solid Films, 1998, 327–329, 423.
20. (a) G. J. Ashwell, E. J. C. Dawnay, A. P. Kuczynski and P. J. Martin, Proc. SPIE-Int. Soc. Opt. Eng., 1991, 1361, 589; (b) G. J. Ashwell, Spec. Publ. R. Soc. Chem., 1993, 137, 31.
21. (a) S. Ma, K. Han, X. Lu, W. Wang, Z. Zhang and Z. Yao, Opt. Commun., 1994, 111, 513; (b) S. Ma, X. Lu, J. Xu, W. Wang and Z. Zhang, J. Phys. D, 1997, 30, 2651.
22. G. J. Ashwell, P. D. Jackson, D. Lochun, P. A. Thompson, W. A. Crossland, G. S. Bahra, C. R. Brown and C. Jasper, Proc. R. Soc. London A, 1994, 445, 385.
23. P. Hodge, Z. Ali-Adib, D. West and T. King, Macromolecules, 1993, 26, 1789.
24. P. Hodge, Z. Ali-Adib, D. West and T. King, Thin Solid Films, 1994, 244, 1007.
25. G. Wang, J. Wen, X. Lu, L. Liu, W. Wang, Y. Huang, H. Al, Y. Fang and F. Tao, J. Phys. D, 1995, 28, 2113.
26. I. Cabrera, A. Mayer, D. Lupo, U. Falk, U. Scheunemann and W. Hickel, Nonlinear Opt., 1995, 9, 161.
27. (a) M. Era, K. Nakamura, T. Tsutsui, S. Saito, H. Niino, K. Takehara, K. Isomura and H. Tanaguchi, Jpn. J. Appl. Phys., 1990, 29, L2261; (b) M. Era, H. Kawafuji, T. Tsutsui, S. Saito, K. Takehara, K. Takehara, K. Isomura and H. Taniguchi, Thin Solid Films, 1992, 210–211, 163.
28. G. J. Ashwell, P. D. Jackson and W. A. Crossland, Nature, 1994, 368, 438.
29. (a) G. J. Ashwell, P. D. Jackson and C. Jasper, Nonlinear Opt., 1995, 14, 121; (b) G. J. Ashwell, P. D. Jackson, G. Jefferies, I. R. Gentle and C. H. L. Kennard, J. Mater. Chem., 1996, 6, 137.
30. G. J. Ashwell, D. Lochun, I. R. Gentle, C. H. L. Kennard, G. S. Bahra and C. R. Brown, Supramol. Sci., 1995, 2, 131.
31. G. J. Ashwell, T. Handa and R. Ranjan, J. Opt. Soc. Am. B, 1998, 15, 466.
32. G. J. Ashwell, D. Zhou and K. Skjonnemand, Mol. Cryst. Liq. Cryst., in the press.
33. (a) G. J. Ashwell, G. Jefferies, C. D. George, R. Ranjan, R. B. Charters and R. P. Tatam, J. Mater. Chem., 1996, 6, 131; (b) G. J. Ashwell, G. Jefferies and R. Ranjan, Electron. Lett., 1996, 32, 59.
34. G. J. Ashwell and R. Ranjan, Proc. SPIE-Int. Soc. Opt. Eng., 1998, 3474, 76.
35. C. W. Pitt and L. M. Walpita, Thin Solid Films, 1980, 68, 101.
36. (a) C. Bosshard, M. Küpfer, P. Günter, C. Pasquier, S. Zahir and M. Siefert, Appl. Phys. Lett., 1990, 56, 1204; (b) C. Bosshard, M. Küpfer, M. Flörsheimer, P. Günter, C. Pasquier, S. Zahir and M. Siefert, Makromol. Chem.-Macromol. Symp., 1991, 46, 27.
37. (a) C. Bosshard, M. Flörsheimer, M. Küpfer and P. Günter, Opt. Commun., 1991, 85, 247; (b) M. Flörsheimer, M. Küpfer, C. Bosshard and P. Günter, in Nonlinear Optics: Fundamentals, Materials and Devices, Proc. 5th Toyota Conf. Nonlinear Opt., ed. S. Miyata, Elsevier, Amsterdam, 1992, 255.
38. (a) M. Flörsheimer, M. Küpfer, C. Bosshard, H. Looser and P. Günter, Adv. Mater., 1992, 4, 795; (b) M. Küpfer, M. Flörsheimer, C. Bosshard, H. Looser and P. Günter, Proc. SPIE-Int. Soc. Opt. Eng., 1993, 1775, 340.
39. C. Bosshard, A. Otomo, G. I. Stegeman, M. Küpfer, M. Flürsheimer and P. Günter, Appl. Phys. Lett., 1994, 64, 2076.
40. (a) M. Küpfer, M. Flörsheimer, C. Bosshard and P. Günter, Electron. Lett., 1993, 29, 2033; (b) M. Küpfer, M. Flörsheimer, C. Bosshard and P. Günter, Nonlinear Opt., 1995, 10, 341.
41. (a) N. Asai, H. Tamada, I. Fujiwara and J. Seto, J. Appl. Phys., 1992, 10, 4521; (b) I. Fujiwara, N. Asai and V. Howarth, Thin Solid Films, 1992, 221, 285; (c) N. Asai, I. Fujiwara, H. Tamada and J. Seto, Mater. Res. Soc. Symp. Proc., 1994, 328, 91.
42. (a) T. L. Penner, H. R. Motschmann, N. J. Armstrong, M. C. Ezenyilimba and D. J. Williams, Nature, 1994, 367, 49; (b) K. Clays, N. J. Armstrong, M. C. Ezenyilimba and T. L. Penner, Chem. Mater., 1993, 5, 1032.
43. (a) T. L. Penner, N. J. Armstrong, C. S. Willand, J. S. Schildkraut and D. R. Robello, Proc. SPIE-Int. Soc. Opt. Eng., 1991, 1560, 377; (b) K. Clays, T. L. Penner, N. J. Armstrong and D. R. Robello, Proc. SPIE-Int. Soc. Opt. Eng., 1992, 1775, 326; (c) T. L. Penner, N. J. Armstrong, C. S. Willand, J. S. Schildkraut, D. R. Robello and A. Ulman, Nonlinear Opt., 1993, 4, 191; (d) K. Clays, N. J. Armstrong and T. L. Penner, J. Opt. Soc. Am. B, 1993, 10, 886.
44. (a) W. Hickel, B. Menges, O. Althoff, D. Lupo, U. Falk and U. Scheunemann, Thin Solid Films, 1994, 244, 966; (b) W. Hickel, J. Bauer, D. Lupo, B. Menzel, U. Falk and U. Scheunemann, Spec. Publ. R. Soc. Chem., 1993, 137, 80.
45. S. Fujita, T. Watanabe, K. Shigehara and S. Miyata, Nonlinear Opt., 1996, 15, 493.
46. D. M. Nguyen, T. M. Mayer, S. F. Hubbard, K. D. Singer, J. A. Mann and J. B. Lando, Macromolecules, 1997, 30, 6150.
47. S. S. Johal, S. W. James, R. P. Tatam and G. J. Ashwell, Opt. Lett., in the press.
48. (a) R. H. Selfridge, S. T. Kowel, P. Stroeve, J. Y. S. Lam and B. G. Higgins, Thin Solid Films, 1988, 160, 471; (b) R. H. Selfridge, T. K. Moon, P. Stroeve, J. Y. S. Lam, S. T. Kowel and A. Knoesen, Proc. SPIE-Int. Soc. Opt. Eng., 1988, 971, 197.
49. (a) G. J. Ashwell, E. J. C. Dawnay, A. P. Kuczynski, M. Szablewski, I. M. Sandy, M. R. Bryce, A. M. Grainger and M. Hasan, J. Chem. Soc., Faraday Trans., 1990, 86, 1117; (b) G. J. Ashwell, G. Jefferies, E. J. C. Dawnay, A. P. Kuczynski, D. E. Lynch, G. Yu and D. G. Bucknall, J. Mater. Chem., 1995, 5, 975.
50. (a) M. A. Rutkis, E. Wistus, S. E. Lindquist, E. Mukhtar, G. Liberts, V. Zauls, A. B. Klimkans and E. A. Silinsh, Adv. Mater. Opt. Electron., 1996, 6, 39; (b) E. A. Silinsh, Proc. SPIE-Int. Soc. Opt. Eng., 1997, 2968, 24; (c) G. Liberts, V. Zauls and N. Ojars, Proc. SPIE-Int. Soc. Opt. Eng., 1997, 2968, 19.
51. F. Grunfeld, Rev. Sci. Instrum., 1993, 64, 548.
52. G. J. Ashwell, G. S. Bahra, C. R. Brown, D. G. Hamilton, C. H. L. Kennard and D. E. Lynch, J. Mater. Chem., 1996, 6, 23.
53. J. Bernstein and E. Goldstein, Mol. Cryst. Liq. Cryst., 1988, 164, 213.
54. C. W. Dirk, W. C. Herndon, F. Cervantes-Lee, H. Selnau, S. Martinez, P. Kalamegham, A. Tan, G. Campos, M. Velez, J. Zyss, I. Ledoux and L.-T. Cheng, J. Am. Chem. Soc., 1995, 117, 2214.
55. G. J. Ashwell, P. C. Williamson, G. S. Bahra and C. R. Brown, Aust. J. Chem., 1999, 52, 37.
56. G. J. Ashwell, G. M. S. Wong, D. G. Bucknall, G. S. Bahra and C. R. Brown, Langmuir, 1997, 13, 1629.
57. G. J. Ashwell, A. N. Dyer and A. Green, Langmuir, 1999, 15, 3627.
58. (a) J.-L. Brédas and E. Brouyère, private communication; (b) E. Brouyère, PhD Thesis, Université de Mons-Hainaut, 1997.
59. C. L. Honeybourne, J. Mater. Chem., 1999, 2241.
60. H. Chen, W. G. Herkstroeter, J. Perlstein, K. Y. Law and D. G. Whitten, J. Phys. Chem., 1994, 98, 5138.
61. G. J. Ashwell, G. Jefferies, N. D. Rees, P. C. Williamson, G. S. Bahra and C. R. Brown, Langmuir, 1998, 14, 2850.
62. G. J. Ashwell, J. Mater. Chem., 1998, 8, 373.
63. G. J. Ashwell, P. Leeson, G. S. Bahra and C. R. Brown, J. Opt. Soc. Am. B, 1998, 15, 484.
64. G. J. Ashwell, P. C. Williamson, A. Green, G. S. Bahra and C. R. Brown, Aust. J. Chem., 1998, 51, 599.
65. H. Chen, K. Y. Law and D. G. Whitten, J. Phys. Chem., 1996, 100, 5949.
66. (a) T. Bjørnholm, T. Geisler, J. Larsen and M. Jørgensen, J. Chem. Soc., Chem. Commun., 1992, 815; (b) T. Bjørnholm, T. Geisler, J. Larsen, M. Jørgensen, K. Brunfeldt, K. Schaumburg and K. Bechgaard, Synth. Met., 1993, 57, 3813; (c) T. Geisler and T. Bjørnholm, Synth. Met., 1993, 57, 3842.
67. (a) D. B. Neal, M. C. Petty, G. G. Roberts, M. M. Ahmad, W. J. Feast, I. R. Girling, N. A. Cade, P. V. Kolinski and I. R. Peterson, Electron. Lett., 1986, 22, 460; (b) D. B. Neal, M. C. Petty, G. G. Roberts, M. M. Ahmad, W. J. Feast, I. R. Girling, N. A. Cade, P. V. Kolinski and I. R. Peterson, Proc. 6th IEEE Int. Symp. Appl. Ferroelectr., 1986, 89.
68. G. J. Ashwell, D. Zhou, K. Skjonnemand, R. Ranjan, C. Huang and T. Cheng, Langmuir, in the press.
69. S. Allen, T. McLean, P. F. Gordon, B. D. Bothwell, P. Robin and I. Ledoux, Proc. SPIE-Int. Soc. Opt. Eng., 1988, 971, 206.
70. I. Ledoux, D. Josse, P. Fremaux, J.-P. Piel, G. Post, J. Zyss, T. McLean, R. A. Hann, P. F. Gordon and S. Allen, Thin Solid Films, 1988, 160, 217.
71. (a) R. M. Swart, E. S. Froggatt, A. N. Burgess, A. Eaglesham, D. P. Devonald, M. G. Hutchins, S. Allen and T. G. Ryan, Thin Solid Films, 1992, 210–211, 237; (b) J. P. Cresswell, M. C. Petty, J. E. Shearman, S. Allen, T. G. Ryan and I. Ferguson, Thin Solid Films, 1994, 244, 1067; (c) C. H. Wang, B. S. Wherrett, J. P. Cresswell, M. C. Petty, T. G. Ryan, S. Allen, I. Ferguson, M. G. Hutchins and D. P. Devonald, Opt. Lett., 1995, 14, 1533; (d) J. P. Cresswell, M. C. Petty, I. Ferguson, M. G. Hutchins, S. Allen, T. G. Ryan, C. H. Wang and B. S. Wherrett, Adv. Mater. Opt. Electron., 1996, 6, 33.
72. (a) R. C. Hall, G. A. Lindsay, B. L. Anderson, S. T. Kowel, B. G. Higgins and P. Stroeve, Mater. Res. Soc. Symp. Proc., 1988, 109, 351; (b) B. L. Anderson, R. C. Hall, B. G. Higgins, G. A. Lindsay, P. Stroeve and S. T. Kowell, Synth. Met., 1989, 28, D683.
73. M. J. Roberts, G. A. Lindsay, K. J. Wynne, R. A. Hollins, P. Zarras, J. D. Stenger-Smith, M. Nadler and A. P. Chafin, Polym. Prepr., 1997, 38, 975.
74. H. R. Motschmann, T. L. Penner, N. J. Armstrong and M. C. Ezenyilimba, J. Phys. Chem., 1993, 97, 3933.
75. W. M. K. P. Wijekoon, S. K. Wijaya, J. D. Bhawalkar, P. N. Prasad, T. L. Penner, N. J. Armstrong, M. C. Ezenyilimba and D. J. Williams, J. Am. Chem. Soc., 1996, 118, 4480.
76. (a) G. A. Lindsay, K. J. Wynne, W. N. Herman, A. P. Chafin, R. A. Hollins, J. D. Stenger-Smith, J. Hoover, J. Cline and M. J. Roberts, Nonlinear Opt., 1996, 15, 139; (b) G. A. Lindsay, M. J. Roberts, J. D. Stenger-Smith, W. N. Herman, P. R. Ashley and K. J. Wynne, Nav. Res. Rev., 1997, XLIX, 21; (c) W. N. Herman, M. J. Roberts, J. D. Stenger-Smith, A. P. Chafin, R. A. Hollins, G. A. Lindsay and K. J. Wynne, Polym. Prepr., 1998, 39, 1105.
77. G. J. Ashwell, R. C. Hargreaves, C. E. Baldwin, G. S. Bahra and C. R. Brown, Nature, 1992, 357, 393.
78. M. C. J. Young, R. Jones, R. H. Tredgold, W. X. Lu, Z. Ali-Adib, P. Hodge and F. Abbasi, Thin Solid Films, 1989, 182, 319.
79. X. Liu, L. Liu, Z. Chen, X. Lu, J. Zheng and W. Wang, Thin Solid Films, 1992, 219, 221.
80. I. R. Girling, N. A. Cade, P. V. Kolinski, R. J. Jones, I. R. Peterson, M. M. Ahmad, D. B. Neal, M. C. Petty, G. G. Roberts and W. J. Feast, J. Opt. Soc. Am. B, 1987, 4, 950.
81. L. M. Hayden, Phys. Rev. B, 1988, 38, 3718.
82. (a) J. S. Schildkraut, T. L. Penner, C. S. Willand and A. Ulman, Opt. Lett., 1988, 13, 134; (b) M. A. Carpenter, C. S. Willand, T. L. Penner, D. J. Williams and S. Mukamel, J. Phys. Chem., 1992, 96, 2801.
83. G. J. Ashwell, T. W. Walker, I. R. Gentle, G. Foran, G. S. Bahra and C. R. Brown, J. Mater. Chem., 1996, 6, 969.
84. F. Davis, P. Hodge, X.-H. Liu and Z. Ali-Adib, Macromolecules, 1994, 27, 1957.
85. K. Han, X. Lu, J. Xu, S. Ma and W. Wang, Opt. Commun., 1998, 152, 371.
86. L. M. Hayden, B. L. Anderson, J. Y. S. Lam, B. G. Higgins, P. Stroeve and S. T. Kowell, Thin Solid Films, 1988, 160, 379.
87. L. Liu, J. Zheng, W. Wang, Z. Zhang, F. Tao, L. Xu and J. Hu, Opt. Commun., 1992, 93, 207.
88. D. Dunne, P. Hodge, Z. Ali-Adib, N. B. McKeown and D. West, J. Mater. Chem., 1998, 8, 1391.
89. (a) B. L. Anderson, J. M. Hoover, G. A. Lindsay, B. G. Higgins, P. Stroeve and S. T. Kowel, Thin Solid Films, 1989, 179, 413; (b) R. C. Hall, G. A. Lindsay, S. T. Kowel, L. M. Hayden, B. L. Anderson, B. G. Higgins, P. Stroeve and M. P. Srinivasan, Proc. SPIE-Int. Soc. Opt. Eng., 1987, 824, 121.
90. (a) M. C. J. Young, W. X. Lu, R. H. Tredgold, P. Hodge and F. Abbasi, Electron. Lett., 1990, 26, 993; (b) M. Bardosova, F. Davis, R. H. Tredgold, Z. Ali-Adib, B. Hunt and V. Shmatko, Thin Solid Films, 1994, 244, 740.
91. J. P. Cresswell, M. C. Petty, C. H. Wang, B. S. Wherrett, Z. Ali-Adib, P. Hodge, T. G. Ryan and S. Allen, Opt. Commun., 1995, 115, 271.
92. G. J. Ashwell, K. R. Ranjan, A. J. Whittam and D. Gandolfo, J. Mater. Chem., in the press.
93. J. F. McGilp, Z. R. Tang and M. Cavanagh, Synth. Met., 1993, 61, 181.
94. G. J. Ashwell and A. J. Whittam, Mol. Cryst. Liq. Cryst., in the press.
95. G. J. Ashwell, T. W. Walker, P. Leeson, U.-W. Grummt and F. Lehmann, Langmuir, 1998, 14, 1525.
96. M. A. Schoondorp, A. J. Schouten, J. B. E. Hulshof and B. L. Feringa, Langmuir, 1993, 9, 1323.
97. S. Allen, T. G. Ryan, D. P. Devonald, M. G. Hutchings, A. N. Burgess, E. S. Froggatt, A. Eaglesham, R. M. Swart, G. J. Ashwell and M. Malhotra, Spec. Publ. R. Soc. Chem., 1991, 91, 51.
98. (a) M. Conroy, Z. Ali-Adib, P. Hodge, D. West and T. King, J. Mater. Chem., 1994, 4, 1; (b) D. West, D. Dunne, P. Hodge, N. B. McKeown and Z. Ali-Adib, Thin Solid Films, 1998, 323, 227.
99. R. H. Tredgold, M. C. J. Young, R. Jones, P. Hodge, P. Kolinski and R. J. Jones, Electron. Lett., 1988, 24, 308.
100. Y. Liu, Y. Xu, D. Zhu, T. Wada, H. Sasabe, X. Zhao and X. Xie, J. Phys. Chem., 1995, 99, 6957.
101. (a) H. Sakaguchi, H. Nakamura, T. Nagamura, T. Ogawa and T. Matsuo, Chem. Lett., 1989, 1715; (b) H. Sakaguchi, T. Nagamura, T. L. Penner and D. G. Whitten, Thin Solid Films, 1994, 244, 947.
102. H. Hsiung, J. Rodriguez-Parada and R. Beckerbauer, Chem. Phys. Lett., 1991, 182, 88.
103. C. Bubeck, A. Laschewsky, D. Lupo, D. Neher, P. Ottenbreit, W. Paulus, W. Prass, H. Ringsdorf and G. Wegner, Adv. Mater, 1991, 3, 54.
104. O. A. Aktsipetrov, E. D. Mishina, T. V. Misuryaev, A. A. Nikulin, V. R. Novak, R. Stolle and T. Rasing, Surf. Sci., 1998, 402–404, 576.
105. M. J. Roberts, G. A. Lindsay, J. D. Stenger-Smith, R. A. Hollins, A. P. Chafin and R. G. Gratz, Thin Solid Films, 1998, 327–329, 5.
106. (a) R. Popovitz-Biro, K. Hill, E. M. Landau, M. Lahav, L. Lieserowitz, J. Sagiv, H. Hsiung, G. R. Meredith and H. Vanherzeele, J. Am. Chem. Soc., 1988, 110, 2672; (b) R. Popovitz-Biro, K. Hill, E. Shavit, M. Lahav, L. Lieserowitz, J. Sagiv, H. Hsiung, G. R. Meredith and H. Vanherzeele, J. Am. Chem. Soc., 1990, 112, 2498.
107. T. Richardson, G. G. Roberts, M. E. C. Polywka and S. G. Davies, Thin Solid Films, 1988, 160, 231.
108. T. Senoh, K. Sanui and N. Ogata, Chem. Lett., 1990, 1849.
109. L. M. Hayden, S. T. Kowel and M. P. Srinivasan, Opt. Commun., 1987, 61, 351.
110. I. Ledoux, D. Josse, P. Vidakovic, J. Zyss, R. A. Hann, P. F. Gordon, B. D. Bothwell, S. K. Gupta, S. Allen, P. Robin, E. Chastaing and J.-C. Dubois, Europhys. Lett., 1987, 3, 803.
111. N. Kalita, J. P. Cresswell, M. C. Petty, A. McRoberts, D. Lacey, G. Gray, M. J. Goodwin and N. Carr, Opt. Mater., 1992, 1, 259.
112. K. Isomura, K. Takehara, K. Kobayashi, G. Funakoshi, H. Taniguchi, M. Era, T. Tsutsui and S. Saito, Thin Solid Films, 1994, 244, 939.
113. Y. Liu, Y. Xu, D. Zhu, T. Wada, H. Sasabe, L. Liu and W. Wang, Thin Solid Films, 1994, 244, 943.
114. D.-W. Cheong, W.-H. Kim, L. A. Samuelson, J. Kumar and S. K. Tripathy, Macromolecules, 1996, 29, 1416.
115. (a) O. A. Aktsipetrov, N. N. Akhmediev, E. D. Mishina and V. R. Novak, JETP Lett., 1983, 37, 207; (b) O. A. Aktsipetrov, N. N. Akhmediev, I. M. Baranova, E. D. Mishina and V. R. Novak, Sov. Phys. JETP (Engl. Transl.), 1985, 62, 524.
116. A. Watakabe, H. Okada and T. Kunitake, Langmuir, 1994, 10, 2722.
117. D.-W. Cheong, J.-I. Chen, J. Kumar and S. K. Tripathy, Mater. Res. Soc. Symp. Proc., 1996, 413, 81.
118. M. N. Teerenstra, J. G. Hagting, A. J. Schouten, R. J. M. Nolte, M. Kauranen, T. Verbiest and A. Persoons, Macromolecules, 1996, 29, 4876.
119. (a) G. J. Ashwell, J. R. Sambles, A. S. Martin, W. G. Parker and M. Szablewski, J. Chem. Soc., Chem. Commun., 1990, 1374; (b) A. S. Martin, J. R. Sambles and G. J. Ashwell, Phys. Rev. Lett., 1993, 70, 218.
120. R. M. Metzger, B. Chen, U. Hopfner, M. V. Lakshmikantham, D. Vuillaume, T. Kawai, X. Wu, H. Tachibana, T. V. Hughes, H. Sakurai, J. W. Baldwin, C. Hosch, M. P. Cava, L. Brehmer and G. J. Ashwell, J. Am. Chem. Soc., 1997, 119, 10455.
121. Langmuir-Blodgett Films, ed. G. G. Roberts, Plenum Press, New York, 1990.
122. A. Ulman, An Introduction to Ultrathin Films: from Langmuir-Blodgett to Self-Assembly, Academic Press, San Diego, 1991.
123. M. C. Petty, Langmuir-Blodgett Films: an Introduction, Cambridge University Press, Cambridge, 1996.
124. G. J. Ashwell, D. Lochun and A. N. Dyer, Mol. Cryst. Liq. Cryst., in the press.
125. G. J. Ashwell, D. Zhou and K. Skjonnemand, Langmuir, submitted for publication.
126. S. S. Johal, S. W. James, R. P. Tatam and G. J. Ashwell, Meas. Sci. Technol., 1999, 10, N60.