A study on the optical absorption properties of dielectric-mediated gold nanoshells

Optical absorption properties of dielectric-mediated gold nanoshells were studied experimentally and theoretically. Sodium dodecylbenzenesulfonate (ABS) mediated colloidal gold nanoshells have been prepared via reduction of chlorauric acid (HAuCl4) by sodium citrate in the presence of ABS as a capping agent. Compared with pure gold nanospheres, the plasmon resonance absorption peak of the gold–dielectric core–shell structure nanospheres red shift and get wider and intensive. Numerical calculations based on Drude model and quasi-static theory indicated that, the absorbance peak red shifts nonlinearly with increasing dielectric shell thickness. Further more, the intensity and full-width at half-maximum (FWHM) of the absorbance peak also increase nonlinearly. However, with increase shell thickness, all these variation get gentle and gentle and approach a constant value when the shell thickness is greater than the core radius.