Fluorescent dyes mixed with liquid crystals in Langmuir and Langmuir-Blodgett films

Langmuir and Langmuir-Blodgett films of various dyes, namely derivatives of: 3,4,9,10-perylenetetracarboxylic acid, 3,4,9-perylenetricarboxylic acid, naphthalenebicarboxylic acid and naphthoylenebenzimidazole as well as of their mixtures with a liquid crystal were investigated. The dependence of the surface pressure -- on the mean molecular area for Langmuir films was measured, from which the molecular organization and the miscibility of components in the monomolecular layer at the air-water interface were determined. For Langmuir-Blodgett films the absorption and emission spectra were recorded and information about the spectral properties and molecular alignment of dyes and liquid crystals in ultrathin layers at solid substrates was obtained.