Immobilization of polyynes adsorbed on Ag nanoparticle aggregates into poly(vinyl alcohol) films

Composite films of poly(vinyl alcohol) containing polyynes adsorbed on aggregates of Ag nanoparticles were prepared and the stability of the Ag aggregates and polyynes was investigated by measuring the time evolution of absorption and surface-enhanced Raman spectra. The results indicate that the embedded aggregates of Ag nanoparticles and adsorbed polyynes are stable for a month. The high stability of the composite films made it possible to obtain an excitation profile of the surface-enhanced Raman spectrum. The excitation profile could be well reproduced by a theoretical calculation based on the electromagnetic mechanism of surface-enhanced Raman scattering.