Photoinduced modification of component composition of molecular layers with silver nanoparticles

摘要

Photonic properties and photoinduced transformations of hybrid materials comprising silver nanoparticles and polymethine dye layers were studied. Granular films were obtained via thermal evaporation of Ag on transparent substrates in a vacuum. Polymethine dye was spin-coated over the Ag films. The samples were characterized by optical spectroscopy, confocal fluorescent and scanning electron microscopy. Transformations of polymethine dye molecules were studied under the action of pulsed and cw laser irradiation. The threshold of laser induced transformations of dye molecules in hybrid films was found to be much lower than that for the bare dielectric substrate under the action of Nd: YAG laser second harmonic pulses. In the case of a hybrid film, transformations lead to the increased absorption in the J-aggregate band while the dye layers on a bare substrate experience, albeit 3.5 times smaller, decrease of absorption. Enhancement of absorption and fluorescence of dyes in the fields of Ag nanoparticles was observed.