Precise measurement of gold nanorods by using depolarized dynamic light scattering apparatus

A precise and noninvasive method for the size and shape measurement of gold nanorods (GNRs) has been proposed based on depolarized dynamic light scattering (DDLS). A home-made DDLS apparatus has been established. By applying depolarized optical path with precise alignment method, the signal-to-noise ratio (SNR) of this apparatus is highly improved. GNRs with three different diameter and length has been precisely measured by using DDLS method as well as scanning electron microscopy (SEM). The thickness of adsorption layer of cetyltrimethylammonium bromide (CTAB) in solution has been taken into consideration. Results show that size measurement of GNRs by using DDLS method agrees very well with that by using SEM. In addition, it is shown that the extinction spectroscopy strongly limited the application of DDLS method by affecting the effective scattering light intensity. Proper laser wavelength should be chosen before the application of this method.