Influence of Compression Processes on the Formation of H-Aggregates in Hemicyanine Monolayer on Water Surface

The influence of the compression process on the formation of H-aggregates has been studied by means of the absorption spectra of the hemicyanine monolayer on the water surface. It was found that the conventional compression by moving the barrier does not bring about the formation of the H-aggregates but that the compression by spreading the dye solution does cause the formation. Absorption spectra in several geometries reveal that most of the aggregated molecules deposited on a substrate (LB film) are aligned along the surface normal and that the molecules on water (L film) tilt from the water-surface normal.