It should be noted that nanoparticles coated with two diazonium salts (AB and DMB) at a total concentration of 10 -3 M were very highly aggregated, and thus could not be characterized. Figure shows the organic layer around gold NPs with an average thickness of 1.8 nm for NPs/AB:DMB 10 -4 M; a thinner 1 nm aryl layer was obtained for an initial diazonium concentration of 510 -5 M. In Figure , the thickness of organic layer is shown at a concentration of 10 -4 M of AB:DMB salt mixture, which is more visible at higher concentrations of diazonium salts than the lower concentrations. In this regard, for two diazonium salts with a concentration of 510 -5 M, there is a better dispersion than in the case of 10 -4 M concentration.