Methods Figure 1 shows the

configuration of the Au-SiO2-Au nanomatryoshka, which consists of an SiO2 layer between an Au core and an Au shell, excited by a radial electric dipole or illuminated by polarized light. The outer radius of the Au shell, the radius of the middle silica layer, and the radius of the Au core are denoted by a 1, a 2, and a 3, respectively. The thicknesses of the outer Au shell and the silica interlayer are denoted by t 1 and t 2, respectively, CH5183284 research buy where t 1  = a 1  - a 2, t 2  = a 2  - a 3. Without loss of generality, the radial dipole is a distance d above the north pole of the nanomatryoshka, and the incident plane wave is assumed to propagate along the y-axis with a z-polarized electric field. The origin of the coordinate system is located at the center of the Au core. Throughout this paper, the classical theory of Maxwell’s equations is used to analyze the electromagnetic field that is induced by an electric dipole or a plane wave that irradiates a nanomatryoshka. An analytical solution of the dyadic Green’s functions is used in the former case [22], and the Mie theory is used in the latter case [23]. In response to the interaction of a radial dipole with the nearby nanomatryoshka, the radiative power can be expressed by (1) where the integral surface S can be any arbitrary closed

BMS-907351 cost surface that encloses the nanomatryoshka and the electric dipole [23]. The nonradiative power due to the ohmic loss in the nanomatryoshka is the dissipation power in metal, (2) where S m represents the outer surface of the Au shell [6, 23]. Here, the unit normal is outward. Since the silica layer and its surrounding Nintedanib (BIBF 1120) medium are lossless media, the nonradiative power is the total power dissipated in the Au shell and core, which can be decomposed

into . The dissipation power in the Au core is given by (3) where S c is the surface of the Au core. The multi-connected surface of the Au shell is S m∪S c. Equations 2 and 3 can be used to analyze individually the contributions of the Au shell and the Au core. Figure 1 Configuration of Au-SiO 2 -Au nanomatryushka irradiated by a radial electric dipole or a z -polarized plane wave. The radii of the outer Au shell, the SiO2 shell, and the Au core are denoted by a 1, a 2, and a 3, respectively. Moreover, the Fano line-shape function in terms of wavelength λ is defined as (4) where [10–12]. In Equation 4, q, λ 0, and δ f are the Fano factor, the central wavelength, and the bandwidth, respectively. Here, A is a constant for amplitude. Below, this profile will be used to fit the spectra of the nonradiative powers or absorption efficiencies of the Au shell and the Au core at the Fano resonance. Results and Selleckchem MAPK inhibitor discussion The plasmon modes of a typical nanomatryoshka of size [a 1, a 2, a 3] = [75, 50, 35] nm are analyzed first. The surrounding medium is water. The permittivity of Au is taken from the literature [24].