Interactions between a single metallic nanoparticle and chiral molecular J-aggregates in the strong coupling regime and the weak coupling regime

Abstract

We theoretically investigate the coupling between a single Ag nanoparticle and chiral molecular J-aggregates (TDBC). The element of the structure is composed of a Ag nanoparticle entirely surrounded by chiral TDBC. The results show that the coupling between the Ag nanoparticle and TDBC can be tuned by the size of the Ag nanoparticle. By changing the size of the Ag nanoparticle, both the strong coupling effect and the weak coupling effect between the Ag nanoparticle and TDBC are achieved. Circular dichroism (CD) spectra of the hybridized structures in both the strong and the weak coupling regimes present a Fano line-shape, which can be represented in the form of . We also find that the CD spectrum in the strong coupling regime is less than that in the weak coupling regime. The maximum of the CD spectrum of the hybridized structure in the scattering spectrum is amplified 130 times compared to that of chiral TDBC in the strong coupling regime, and 490 times compared to that in the weak coupling regime, respectively. Much more energy is used to change the resonant wavelength of the hybridized structure in the strong coupling regime. The radiative efficiency of the system is suppressed. In the weak coupling regime, the energy is mainly used to enhance the CD spectrum. Our research has great potential for molecule detection.