Terahertz multispectral imaging for the analysis of gold nanoparticles’ size and the number of unit cells in comparison with other techniques

Abstract

In this work, we investigate the use of a Terahertz multispectral reconstructive imaging technique to measure the size of individual gold nanoparticles and accordingly the number of unit cells in a given gold nanoparticle. The gold nanoparticles were synthesized by the Frens-Turkevich citrate method and characterized by UV-Vis absorption spectroscopy, Dynamic light Scattering, and Transmission Electron Microscopy as well as by terahertz 3D image analysis. The size of the gold nanoparticles as determined by the Terahertz reconstructive imaging was 18.5 nm which was comparable to the size obtained by the other aforementioned measurement techniques with the exception of Dynamic light scattering which actually measures the hydrodynamic diameter. Using the size of the gold nanoparticles determined by terahertz reconstructive imaging, the number of unit cells in the gold nanoparticle was computed to be 48,825. The results demonstrate that Terahertz multispectral reconstructive imaging is a powerful nondestructive, non-contact technique for the size analysis of gold nanoparticles.