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

Mercurous ion, Hg-2(2+), are radiolytically reduced in an aqueous solution containing ethylenediaminetetraacetic acid (EDTA) as a ligand. Unlike, in t he case of Ag-2(+) and Tl-2(+), ions, no shift in the absorption band of Hg -2(+) is observed. On irradiation of different ratios of Hg-2(2+) :Ag+ ions in the presence of the ligand, formation of a mixed cluster is observed. I t is concluded that the collective excitation of the electron gas in the mi xed particles contributes to the optical absorption when the concentration of the Ag+ ion is less than that of the Hg-2(2+) ion. In the presence of 1: 1 Hg-2(2+) :Ag+, the electron gas in the silver particles strongly contribu tes to the optical absorption spectrum. Electron microscopy reveals that pa rticles of different sizes between 10-20 nm are present. Experiments with b eta -cyclodextrin show that the hydrophobic cavity of beta -cyclodextrin ca n be utilized for stabilization of such metal clusters. (C) 2001 Elsevier S cience Ltd. All rights reserved.