FT-IR study of Langmuir–Blodgett films of a merocyanine dye: effect of 13C-substitution and influence of J-aggregation

Influence of heat treatment in air, and subsequent hydrothermal treatment in the liquid phase or water treatment in the liquid phase on a mixed Langmuir–Blodgett film of merocyanine dye-arachidic acid-n-octadecane ternary system

“…In 1491 and 1178 cm À1 , and the sharpness of the 1595, 1381, 1315 and 1147 cm À1 bands are ascribed to a remarkable increase in the degree of MS 18 intramolecular charge transfer. As is well known, this increase is characteristic of the J-aggregation in the monolayer and as-deposited LB film of MS 18 [6][7][8]13,14,17]. Consequently, the visible bands in Fig.…”

“…The solid and dotted lines refer to A || and A \ , respectively, and the broken lines correspond to the positions of vibrational bands inherent in the non-aggregated state of MS 18 [8]. Detailed assignments of the MS 18 IR bands are listed in Table 1 [14]. In Fig.…”

“…2b, referring to the information not only on electronic excitation state but also on electronic ground state. The intramolecular charge transfer means the delocalization of p electrons in the butadiene group from the rhodanine group to the benzothiazolydine group [6][7][8][9][12][13][14]17,19], and in the C@S bond in the rhodanine group [6][7][8][9]14] (Fig. 1).…”

“…3a, a weak peak due to the MS 18 free keto group [7,8,[12][13][14]17,19] is discernible near 1680 cm À1 , suggesting that the coupled Cd 2+ ion slightly dissociates from the MS 18 keto group. The result is consistent with that given in our previous paper [8].…”

“…The J-and H-aggregates can be easily controlled in as-deposited LB films of MS 18 [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19], and the former and latter formation mechanisms have been so far elucidated by and our group [6], respectively. Recently, we have attempted conversions from the red-shifted J-to blue-shifted aggregates [7], and from the blue-shifted H-to redshifted aggregates [8] using the perturbation because of the investigation into the possibility of controlling dye aggregation states, and the confirmation of dye alignments of J- [13][14][15] and H-aggregates [6] clarified in the MS 18 LB films.…”