Structural phase transition in two-dimensional polar crystallites of organic dye molecules: In-plane X-ray diffraction analysis

The two-dimensional polar crystallite of amphiphilic merocyanine dye molecules exhibits a thermochromic phase transition on the aqueous subphase. Grazing incident X-ray diffraction measurements were performed onto Langmuir-Blodgett films consisting of the high and/or low temperature phases of the crystallites. It was clarified that the transition accompanies the structural change of the crystallite.