The NPs using at high resolution transmission electron microscopy. Figure shows TEM image pristine (Figure ) and modified gold NPs with diazonium salt AB at concentrations of 10 -3 M, 10 -4 M and 510 -5 M (Figure and). TEM pictures of gold NPs modified with diazonium mixtures (total concentrations 10 -4 M and 510 -5 M) are displayed in Figures and. Compared to pristine nanoparticles, gold NPs modified with diazonium AB at of 10 -3 , 10 -4 and 510 -5 M concentrations, the aryl layer with approximate thicknesses 2.1 and 1.3 and 0.7 nm, respectively. These thicknesses were obtained by measuring an average of 10 different points around the nanoparticles, for about 30 nanoparticles at each concentration through the ImageJ software. This organic layer is reduced by decreasing the concentration of diazonium salts. Concomitant decrease of aggregation of gold NPs was also noted for lower initial diazonium concentration.