Nanoscale molecular clusters coupled to nanostructured surfaces

Abstract

Nanoscale molecular clusters are fascinating fluorescent nanomaterials formed by highly ordered assembly of organic dyes with the optical properties strongly different from those of monomolecules. Hybrid films formed by pseudoisocyanine dye coated metal nanoparticles on a sapphire substrate or nanoporous alumina on an aluminum substrate were studied with steady‐state and time-resolved spectroscopy. On-surface reaction caused isomerization of cyanine molecules as well as self-assembly into molecular nanoclusters, so called J‐aggregates. The excitonic band of clusters had been strongly coupled to plasmonic response of metal nanoparticles. The dynamics of the strong coupling regime was directly analyzed depending on environmental conditions (temperature and presence of gas analyte). The energy transfer of the optical excitation from oxygen vacancies of alumina to the molecular clusters was observed depending on the anodization conditions of the aluminum substrate. Such unique feature should provide a new approach to develop new sensors.