I think this is what we use today. Above post article particles 5 to 100 times smaller.

Light absorption properties of monodispersed micron/nano-sized silver halide emulsions : Cubic silver halide and AgCl {100} T-grain


LI Zhi ; ZHENG Tong ; PENG Bi-Xian ; ...


A silver chloride {100} T-grain emulsion and a series of cubic silver halide emulsions were prepared by varying the parameters correctly during nucleation and growing processes of grains. After the observation of SEM and TEM, following statistical data were obtained: the diameters of the cubic microcrystal are 80, 150, 600 nm respectively, the equivalent circular diameter (ECD) of the {100} tabular microcrystal is 1400 nm and the shape ratio (ratio of ECD to thickness of a grain) is not less than 7. The absorbencies and the relative absorbed energy of the emulsions were calculated and then compared with each other. It can be easily found that the nano-sized AgX microcrystal retained the high light absorption in visible light region and obtained a red shift of its peak, and the absorbance of the AgCl {100} T-grain emulsion was also particular.