Iridium isotopes and their nuclear spins

Summary

The hyperfine structure patterns of some of the significant are lines of iridium have been photographed using as source a hollow cathode tube already described in a paper by the authors on the isotopic constitution of platinum. An examination of the hyperfine structure data of the iridium lines leads to the result that it consists of two isotopes with nuclear spins ½h/2π and 3/2h/2π. A consideration of known facts regarding the occurrence of isotopes of different mass numbers in the various elements has led to the inference that the mass numbers of the two iridium isotopes are 191 and 193 with a relative abundance of nearly 1:2, the isotope with the higher mass number having the higher nuclear spin.