Optical properties of individual nanostructures of molecular J-aggregates

Simultaneous atomic force microscope and reflection micro-spectroscopic study of nanostructures of pseudoisocyanine J-aggregates shows morphology related variety of optical properties in the form of exciton- and polariton-like reflectance spectra. Modulation of the polarization state of incident light is used to study locally the absolute orientations of exciton transition dipole moments. The lowest exciton state assumes a wide range of directions with respect to the long axis of the fibers, from parallel to perpendicular. This behavior is correlated with the onset of polariton-like character of the local reflectance spectra.