Determination of gold concentration in colloids by UV-vis spectroscopy: universality for various nanoparticles and clusters

The UV-vis method is applied to six experimental and theoretical Au models: nanosphere particles and clusters, nanorods, 2D nanotriangles and nanoplates, and 3D nanostars. We fabricated 34 samples with different nanoparticle sizes, shapes, morphology, and Au concentrations. From simulated and experimental data, we derived a universal relation between gold concentration and extinction at $400 \mathrm{~nm}[\mathrm{Au0}](\mathrm{mM})=0.44 \times \mathrm{A}_{400}$.