Size-dependent optical response of complex CoFe@Ag & CoFe@Au core-shell nanospheres

Abstract

Mie theory was used to investigate the optical characteristics at resonance wavelength of complex CoFe@Ag & CoFe@Au core-shell nanoparticles of systematically varied core-sizes between 5–25 nm and shell thickness 2–10 nm. The observed spectra are originating in the wavelength range between 385–398 nm & 518–530 nm with increasing core-sizes of fixed Ag & Au shell thickness. Also, absorption spectra are found in the range of 361–435 nm & 514–532 nm wavelengths with increasing shell thickness of fixed core-sizes. The optical properties of CoFe alloy nanoparticles coated with Ag or Au shell as a function of core size and shell thickness can be tuned and controlled in the visible region of the electromagnetic spectrum and have potential applications in medicine, imaging, and bio-sensing.