研究目的
To determine the optical properties of dimers of metal/J-aggregate nanoparticles and to find new effects in their plexcitonic interaction and near-field electromagnetic coupling of hybrid particles, comprising the dimer.
研究成果
The near-field coupling of plasmonic modes with Frenkel excitons leads to frequency conversion of plasmonic lines to the long-wavelength part of the spectrum, resulting in additional spectral bands that replicate the features of plasmonic bands in bare silver nanoparticles. This phenomenon can be interpreted in terms of fundamental lines and their images, providing new insights for designing high-sensitivity nanosensors based on plasmon-exciton effects.
研究不足
The study is theoretical and relies on computer simulations, which may not fully capture all real-world complexities. The model assumes specific parameters for materials (e.g., dielectric functions) and may not account for all experimental variations or imperfections. The size effect in metallic cores is considered, but other factors like surface roughness or environmental changes are not addressed. The results are specific to the chosen nanoparticle geometry and materials (silver core and TC dye J-aggregate shell).
1：Experimental Design and Method Selection:
The study uses computer simulation based on the finite difference time domain (FDTD) method to solve Maxwell's equations for calculating absorption and scattering cross sections of plexcitonic and plasmonic dimers. A theoretical model is developed using the open-source code library MEEP.
2：Sample Selection and Data Sources:
The dimers consist of two-layer metalorganic nanoparticles with a silver core (radius R = 10 nm) coated with a shell of molecular J-aggregates of cyanine dye TC (thickness h = 5 nm), placed in water. The separation L between centers is varied. For comparison, calculations are also performed for pairs of bare silver nanoparticles.
3：List of Experimental Equipment and Materials:
No physical equipment is used as it is a theoretical study; computational resources are implied.
4：Experimental Procedures and Operational Workflow:
The computation domain is a parallelepiped with absorbing layers. A plane electromagnetic wave with Gaussian pulse time dependence (center wavelength 500 nm) is incident normally. Field dynamics are calculated, and Fourier transforms are applied to obtain spectral components. Absorption and scattering cross sections are computed using Poynting vectors and integration over surfaces.
5：Data Analysis Methods:
The fast Fourier transform is used for spectral analysis. Cross sections are averaged over two polarizations (along and perpendicular to the dimer axis) to simulate naturally polarized light.
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