FT-Raman studies of langmuir-blodgett monolayer components containing absorbing chromophores

Structural studies of Langmuir-Blodgett monolayers and multilayers have revealed that both the hydrophilic and the hydrophobic parts of an amphiphilic molecule can influence the exent of 2-dimensional packing which occurs within a film. In particular, dye chromophores to which are appended long hydrocarbon tails will usually form films dominated by the interaction of the chromophores unless a small amount of hydrocarbon liquid is added. In this case the packing will be dominated by the intermolecular interaction of the hydrocarbon tails. FT-Raman studies of these amphiphilic molecules provides information about both parts of the molecule without resonance enhancement since the laser wavelength used for excitation is far removed from any absorption maxima of the dye chromophore. Specific examples of thiocyanine and merocyanine dyes will be discussed.