Optical Anisotropicity of Core‐Shell or Yolk‐Shell‐typed Ag@Fe3O4 Nanochains

Abstract

Optical anisotropicity of 1‐dimensional nanochains of yolk‐shell (YOSH) and core‐shell (COSH) Ag@Fe3O4 nanoparticles (NPs) is attractive to comprehend electromagnetic relation in different materials in nanoscale regime. To investigate its unique properties, a YOSH Ag@Fe3O4 nanoscale superstructure is prepared through a successive process using COSH‐NPs via a selective etching approach. The Ag‐core can be etched when exposed to a mixture of polyvinylpyrrolidone (PVP) and hydrogen peroxide (H2O2) solution at 25°C. It is investigated that the etching degree of Ag‐core in the COSH‐NPs is linearly correlated with the average molecular weight and amount of PVP and H2O2. In the optical investigation, one‐dimensional YOSH and COSH nanochains are compared to show the dependence of anisotropic plasmonic response on tuning polarized light angle. The YOSH nanochain shows an insensitive plasmonic shift in respect of varying refractive index of solvent, which is probably related with the void of Ag‐yolk and Fe3O4 shell. It is probable that the unique properties of the COSH and YOSH nanochain can be applied to be a potential photonic device and their ultralow quantity sensing and imaging.