Radiolytic production of mercury and silver metal clusters in aqueous solution: a pulse radiolysis study

Mercurous ion, Hg22+, are radiolytically reduced in an aqueous solution containing ethylenediaminetetraacetic acid (EDTA) as a ligand. Unlike, in the case of Ag2+ and Tl2+, ions, no shift in the absorption band of Hg2+ is observed. On irradiation of different ratios of Hg22+:Ag+ ions in the presence of the ligand, formation of a mixed cluster is observed. It is concluded that the collective excitation of the electron gas in the mixed particles contributes to the optical absorption when the concentration of the Ag+ ion is less than that of the Hg22+ ion. In the presence of 1:1 Hg22+:Ag+, the electron gas in the silver particles strongly contributes to the optical absorption spectrum. Electron microscopy reveals that particles of different sizes between 10–20 nm are present. Experiments with β-cyclodextrin show that the hydrophobic cavity of β-cyclodextrin can be utilized for stabilization of such metal clusters.