Hyperfine Structure and Nuclear Spins of Tungsten and Tellurium

By the use of enriched isotopes, hyperfine structure in the optical spectra of Te¹²³, Te¹²⁵, and W¹⁸³ has been observed. Milligram amounts of the isotopes were used in a modified Sch\"uler hollow-cathode discharge tube. In the visible region, 4000 to 6000A, about a dozen lines of singly ionized tellurium showed hyperfine structure, all of them giving just two components for the odd isotope. Te¹²³ and Te¹²⁵ gave identical structures except for a scale factor, the total splitting of the lines of Te¹²³ being about 88 percent of that of Te¹²⁵. In the spectrum of neutral tungsten, all of the lines which show the isotope shift for natural tungsten gave just two components with highly enriched W¹⁸³. The number of hyperfine-structure components, namely two, gives for Te¹²³, Te¹²⁵, and W¹⁸³ a nuclear spin of {}. This was also verified by intensity measurements.