Effect of chemical interface damping and aggregation size of bare gold nanoparticles in NaCl on the plasmon resonance damping

Abstract

The plasmon resonance properties of gold nanoparticles (AuNPs) in liquid ionic medium with different concentration was investigated using a UV-visible/NIR spectrophotometer. The optical absorption spectra of AuNPs suspended in NaCl solutions in the range of 400 – 800 nm were measured; specifically, 10 nm bare AuNPs separately suspended in NaCl solution with molar concentrations of 0.01M and 1M resulted in different shapes and widths in the plasmon resonance peak. The optical spectral resonances were analyzed using the Mie theory, Lorenz-Drude size-dependent dielectric functions and effective medium theory. Analysis of the spectral features by means of theoretical models showed that the damping of the plasmon resonance of AuNPs in ionic medium is size dependent. The experimental results indicated that the effect of chemical interface damping is more prominent compared with the inherent size effects of AuNPs.