Vitaly I. Krasovskii

Resonant plasmon-stimulated nonlinear absorption in three-level systems.

Mechanisms of resonant nonlinear absorption in the hybrid exciton-plasmon systems based on gold nanoparticles and macroheterocyclical compounds are presented. We used novel substituted subphthalocyanines (SubPc) with 14 π-electronic system as powerful excitonic 3 – level systems, and 50 nm gold nanoparticles (AuNp) as plasmonic structures. We succeeded to define mechanisms of resonant nonlinearities and to show that local field factor (LFF) and Purcell factor (PF) lead to dramatic enhancement in SubPc nonlinearity. We suggest a theoretical model which describes exciton-plasmon interaction of porphyrin/phthalocyanine related compounds with gold nanoparticles in the resonant high power laser field.

Strong saturable-absorption effect in subphthalocyanines caused by plasmonic nanoparticles

Nonlinear optical properties of subphthalocyanines coupled with gold nanoparticles have been studied. We have found out many-fold enhancement in the saturable-absorption effect which originated from the strong near-field and great increase in the decay rate of excited states. Such plasmon-induced phenomenon gives the unique opportunity to reduce saturation intensity and boost absorption modulation depth of organic saturable absorbers.

Enhancement of NO2 gas detection in hybrid silver nanoparticles-phthalocyanine thin films

Phthalocyanine-functionalized plasmonic sensing systems are typically based on Kretschmann configuration. Such scheme of detection utilizes spectral or angular modulation of reflected light, which is induced by surface plasmons excitation in the metal film on prism. Phthalocyanines layer plays a role of analyte adsorber. In present paper we offer another approach to phthalocyanine-plasmonic sensing, where both local surface plasmon resonance and optical absorption of phthalocyanines are simultaneously detected. Hybrid Ag nanoparticles (AgNps) - low symmetrical A3B zinc phthalocyanine (ZnPc) thin films were prepared, and their NO2 gas sensitive properties were examined. Since the plasmon resonance of AgNps was properly tuned to charge-transfer band of ZnPc-NO2 complex, we found out more than two-fold increase of the optical response to NO2 exposure in AgNps-ZnPc thin films compared to ZnPc films without AgNps.

Exciton-plasmon interaction in core/shell spherical nanoparticles.

This work reports on the theoretical and experimental research of photophysical properties of hybrid nanostructures based on gold nanoparticles (AuNp) covered by phthalocyanine (Pc) layer. We focused on the theoretical treatment of Pc molecular absorption and luminescence properties. We found out optimal sizes for the hybrid structure core when the maximum of Pc shell molecular absorption is achieved. Optimal core sizes for enhancement of the molecular luminescence were also obtained. AuNp-Pc hybrid structure with average core radius of 10 nm and Pc shell thickness of 2.5 nm were experimentally synthesized. The calculation results were compared with the experimental data, so we obtained well coincidence between each other.

Plasmon-Exciton Interaction in AuNP-Phtalocyanine Core/Shell Nanostructures

We report results of theoretical modeling of photophysical properties of hybrid gold- core nanoparticles (AuNp) covered with the chlor-aluminium phthalocyanine (CAP) shell. The extinction spectra, the near field distribution and the CAP fluorescence quantum yield (QY) changing due to the vicinity to the AuNp were theoretically calculated for different values of the core/shell ratio parameter and compared to experimental data obtained for the structures under consideration.