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Interaction between gold nanoparticle plasmons and aggregates of polymethine dyes: “Invisible” nanoparticles

Research paper by B. I. Shapiro, E. S. Kol’tsova, A. G. Vitukhnovskii, D. A. Chubich, A. I. Tolmachev, Yu. L. Slominskii

Indexed on: 18 Aug '11Published on: 18 Aug '11Published in: Nanotechnologies in Russia



Abstract

Composite nanoparticles consisting of rodlike gold particles coated by an organic layer and polymethine (cyanine) dyes of J-aggregates of different structures absorbing light in red and infrared spectrum ranges have been synthesized. It has been demonstrated that, for dyes with J-band absorption maxima in the gold plasmon-band range, one observes an absorption dip as a result of the interference of the photoexcited states of nanoparticles and J-aggregates. The latter results in the decoloration of the gold colloid solution. The effect of the emergence of new intensive absorption bands of dye aggregates, which is assumed to be related to the perturbance of dye aggregate electron levels by gold plasmons and, consequently, lifting the ban on electron transitions to perturbed levels of aggregates, has been found.