The UV–visible spectroscopy is a commonly used techniques
(Pal et al., 2007). Light wavelengths in the 300–800 nm are generally
used for characterizing various metal nanoparticles in the size range
of 2 to 100 nm (Feldheim and Foss, 2002). Spectrophotometric
absorption measurements in the wavelength ranges of 400–450 nm
(Huang and Yang, 2004) and 500–550 nm (Shankar et al., 2004) are
used in characterizing the silver and gold nanoparticles, respectively.
The dynamic light scattering (DLS) is used to characterize the surface
charge and the size distribution of the particles suspended in a liquid
(Jiang et al., 2009).