Optical properties of molecular layer of cyanine dye coated on Ag or Au island film

Abstract

The absorption properties of molecular layer of cyanine dyes and its J-aggregates coated on the island films in the form of an inhomogeneous ensemble of silver or gold nanoparticles were studied. The different overlapping modes of layer absorption and plasmon resonance were obtained by varying the molecular length and the equivalent thickness of the film. It was shown the absorption of hybrid structure was not a simple sum of overlapping bands. Furthermore, the high enhancement of the molecular absorption was observed due to the influence of the near fields of plasmonic silver nanoparticles in comparison with gold island film. Besides, the induced transparency was observed at the absorption maximum of J-aggregates, which could indicate the interaction between the plasmons of metal nanoparticles and the excitons of the J-aggregate of cyanine dye.