Sub-micron scale spectroscopy and microscopy of individual mesoscopic systems at cryogenic temperatures

We report on a design of a laser scanning solid immersion microscope based on gradient index optics that is suitable for low-temperature excitation sp ectroscopy on the single molecule level. Further, we present a hole-burning study of a system consisting of molecular J-aggregates and associated trap states. These two studies are pre-requisites for microscopic high-resoluti on excitation spectroscopy performed on individual fibers of J-aggregates o f pseudoisocyanine in a polymer film. Preliminary results of the microscopi c study are further compared with microscopic reflection spectroscopy measu red on identical systems at room temperature. (C) 2000 Elsevier Science B.V . All rights reserved.