Isotope shifts and hyperfine structure in the optical spectrum of platinum

The lines $\lambda $444.2 nm, $\lambda $304.2 nm and $\lambda $306.5 nm of the arc spectrum of platinum have been studied under high resolution by using digital recording interferometry. The work extends the range of nuclei for which isotope shifts have been measured to include $^{190}$Pt, and has provided some improvement in accuracy for the shifts involving other isotopes. Data are now available for all the stable platinum nuclei; the relative shifts, which are closely proportional to the changes in mean square radius of the proton distribution, are as follows: 190, 192; $0.905\pm 0.028.\ 192,194;0.969\pm 0.007.\ 194,195;0.456\pm 0.004.\ 194,196;1.0.\ 196,198;1.084\pm 0.004$. The data are discussed in terms of recent measurements of nuclear deformation in platinum. The hyperfine splittings of some levels have also been deduced from the optical measurements.