“…J-aggregates in Langmuir−Blodgett (LB) films of merocyanine dyes, especially 3-carboxy-methyl-5-[2-(3-octadecylbenzothiasolin-2-ylidene)-ethylidene]rhodanine (abbreviated as DS and shown in the inset of Figure ), have attracted much attention because of their interesting properties, such as photoconduction, , in-plane anisotropy, , thermo- and chemichromism, , and nonlinear optics. , The formation mechanism of the J-aggregates has also been studied in LB films of DS − and other merocyanine dyes. ,, As for the pure DS system, which bears one alkyl chain and one carboxylic group, Iriyama et al reported that the J-band is much more distinct on a Cd-containing buffer solution than on pure water, although they could detect a small J-band on pure water. Therefore, buffer solutions containing metal or ammonium cations are commonly used as the subphase for the LB deposition of DS. − An exception to this is the well-developed J-band that has been reported for LB films of a 1:1:1 ternary mixture of DS, fatty acids (FA), and hexadecane, prepared on pure water . However, to our knowledge this ternary system has not been well characterized.…”