Surface-enhanced fluorescence of aggregates in Langmuir-Blodgett monolayers

The geometry of the molecular organization in monolayers seems to be a key factor in the formation of aggregates. In the present work, monolayers of perylene tetracarboxylic derivatives have been fabricated under conditions leading to different molecular orientations in the film. Monolayers of the neat dye material, and mixed monolayers, were prepared at different pH values of the subphase and transferred to glass slides at constant pressure. Monolayers were also transferred to glass substrates at various points in the surface pressure-area isotherm. Steady state surface-enhanced fluorescence measurements were used to characterize the aggregate formation. Surface-enhanced resonant Raman scattering (SERRS) was observed and used as an internal reference in the fluorescence measurements.