Production ofHg198as a Possible Source of an Improved Wave-Length Standard

The green line 5461A from any of the even isotopes of mercury is superior, in many respects, to the red line 6438A of cadmium for a primary standard of wave-length. The mercury isotope of mass 198 was produced by utilizing the nuclear transformation ${}_{79}{}^{}{}_{}{}^{}\mathrm{Au}_{}^{197}{}_{}{}^{}+{}_0{}^{}{}_{}{}^{}n_{}^1{}_{}{}^{}\to {}_{80}{}^{}{}_{}{}^{}\mathrm{Hg}_{}^{198}{}_{}{}^{}+{}_{-1\mathrm{}}{}^{}{}_{}{}^{}\beta _{}^0{}_{}{}^{}$