192Ir is produced by the 191Ir(n, Y)192Ir nuclear reaction. Its half-life is 74 days, and it disintegrates by electron capture and (3_ and gamma radiation. This nuclide has historical importance, as the isotope was used in the discovery of the Mossbauer effect. For more information, see Section 8.8.

8.6.19 Gold-198

198Au is produced by the 197Au(n, Y)198Au nuclear reaction. The half-life is 2.7 days, and it emits (3_ and gamma radiation. 198Au is an ancient radiopharmaceuti­cal; gold colloids have been produced by the reduction of gold salt with ascorbic acid, and they are used in cancer therapy.

8.6.20 Mercury-203

203Hg is produced by the 202Hg(n, Y)203Hg nuclear reaction. Its half-life is 46.6 days, and it emits (3_ and gamma radiation. As a widespread industrial tracer, 203Hg is used to determine the volume of mercury in the cells of natrium chloride electrolysis with mercury cathode (see Section 11.2.4).