Microscopic exciton properties of fibril-shaped molecular J-aggregates prepared in ultra-thin polymer films

摘要

Results on microscopic fluorescence imaging and spectroscopy of fibril-shaped J-aggregates of pseudoisocyanine dyes prepared in thin film matrices of polyvinyl sulfate (PVS) are reported compared with simultaneous observation of the reflection micro-spectroscopy. While the shape of the local reflectance spectra show huge broadening and sometimes dip structures at higher local reflectance levels, we have found that local fluorescence spectra are rather simple and narrow single peak appears at 572 nm or bit longer which is almost coincide with that of ordinary J-band. The result is not inconsistent with the exciton-polariton onset scheme, based on which initial reflectance properties are interpreted. Anomalous local polarization dependences are also observed in fluorescent transition dipoles as in the local reflectance observation, indicating the anomaly is inherent to the fibril formation.