Epitaxial Growth of Merocyanine Dye Molecules on AgBr Surfaces

Abstract

The configuration of photosensitive dye molecules with respect to AgBr lattice is investigated by transmission electron microscopy and electron diffraction, using merocyanine dye (3-ethyl-5-2-(3-ethyl-2-3H)-benzothiazolylidene)-ethylidene]-2-thioxo-4-thiazolidinone; BTET) films vacuum-deposited on (100) and (111) AgBr surfaces. Island and oriented growth of the dye films, in α-phase (triclinic), is found on these AgBr surfaces. The observed epitaxial relations are as follows: (155) [01¯1]BTET//(100)<011>AgBr on the (100) AgBr surface and (011) [ 011]BTET//(111)<101>AgBron the (111) AgBr surface, where the BTET molecules are adsorbed in edge-standing on the AgBr surfaces. The J-absorption peak is observed in optical spectra of these BTET films, which indicates that they form J-aggregates.