Sub-wavelength region spectroscopy and local morphology of individual mesoscopic quantum systems

Results of reflection microscopy and local reflection spectroscopy of J-agg regates of two pseudoisocyanine dyes in a thin film polymer matrix are repo rted. The individual J-aggregates assemble into fibre-like shapes of large structural heterogeneity. Reflectance spectra obtained at different samples , different locations on one sample and even at different positions of the same aggregate fibre reveal a wide distribution of optical properties, The shapes and absolute reflectivities of the spectra are suggested to originat e from varying strengths of exciton-photon interaction and from the effect of finite thickness of the aggregate fibres. Polarization dependence measur ements of local reflectivities provide orientations of the exciton transiti on dipole moments at 572 nm and 540 nm with respect to the orientation of t he aggregate fibres, Furthermore, modified synthesis of capped semiconducto r nanocrystals of CdSe is presented. The method yields high quality quantum dots suitable for microscopic imaging and spectroscopy.