J-aggregates in langmuir-blodgett films of a merocyanine dye without metallic cations: Using FT-IR to observe changes in the electronic structure of the molecules upon aggregation

Journal of Physical Chemistry B

Volumn 103, Issue 51, 1999, Pages 11261-11268

  Ikegami, Keiichi ^a,c   Mingotaud, Christophe ^b   Lan, Minbo ^a  

^a ELECTROTECHNICAL LABORATORY   (Japan)

^b CENTRE DE RECHERCHE PAUL PASCAL   (France)

^c EAST CHINA UNIVERSITY OF SCIENCE AND TECHNOLOGY   (China)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0000719963     PISSN: 15206106     EISSN: None     Source Type: Journal    
DOI: 10.1021/jp991859+     Document Type: Article

References (39)

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26. The surface pressure-area isotherms given by Figure 3 in ref 18 are correct, but the value of the occupied area of DS given in the text, 23 A2, is incorrect: the correct value is 43 A2. This error does not affect the discussion in ref 18, because it is related to the rotating-disc method, not to the characterization of DS-FA films.
27. Aggregation generally changes the electronic structure of both the ground and the excited states. Therefore, the excitation energy, which is the difference between the energies of these states, can vary between the monomeric and the aggregated molecules, even when dipole-dipole interactions between the transition moments are neglected. What we abbreviate to "monomer shift" in this paper corresponds to this effect.
28. The k′ parameter depends on deposition conditions, but its value of 0.77 corresponds to the practical maximum of the Pj(J|substrate) parameter (0.4) of the films formed in this study (See ref 18).
29. 3 solutions described in ref 30. For the aqueous-acetone solution and cast films, the development of J-bands in their spectra complicates the situation, making correlation between their and our results unclear.
30. -1 did not change in these solutions. These results indicate that the observed spectra are due to the monomeric DS and that the shoulder at the higher energy side is a vibronic structure.
31. Bai, C.; Chang, Y.; Xu X. Kexue Tongbao 1983, 28, 1060.
32. Valdes-Aguilera O.; Neckers, D. C. J. Phys. Chem. 1988, 92, 4286.
33. Davidov, A. S. Theory of Molecular Excitations; Plenum: New York, 1971.
34. (34) This phenomenon may be summarized as following. In a dimer of dye molecules, the dipole-dipole interaction between the transition moments creates two new transition moments, whose excitation energies are split. When the molecules in the dimer are not parallel to each other, the orientation of these new transition moments becomes different and therefore both of them are allowed.
35. Fujimoto, Y.; Ozaki, Y.; Takayanagi, M.; Nakata, M.; Iriyama, K. J. Chem. Soc., Faraday Trans. 1996, 92, 413.
36. -1.
37. D). Therefore, the contribution from FA not associated with the aggregates is canceled by the subtraction described by eq 8′.
38. Unfortunately, in ref 16 the static dipoles due to the intramolecular charge transfer and the transition dipoles related to the optical absorption were confused, and the application of the extended dipole model resulted in a questionable conclusion. The application of the extended dipole model to the transition moments is effective for calculating the absorption shifts due to the aggregation. In that case, only the in-phase arrangements of the dipoles (all of the dipoles have the same direction) should be considered, because the oscillator strength associated with the out-of-phase arrangement (half of the dipoles have direction opposite to the others) is zero. However, minimizing the excitaion energy (maximizing the red shift) is useless for the estimation of the molecular arrangements, which is determined by the ground-state energy. To minimize the electrostatic energy of the ground state, the model should be applied to the static dipoles with both in-phase and out-of-phase arrangements. Otherwise, structures such as the one presented in ref 31 are automatically eliminated.
39. Kato, T. Oyobuturi 1999, 68, 541.