Isotope shifts and hyperfine structure in the atomic spectrum of cadmium

The isotope shifts in the spark line $\lambda $ 4416 of cadmium (4d$^{10}$5p$^{2}$P$_{\frac{3}{2}}$-4d$^{9}$5s$^{2\,2}$D$_{\frac{5}{2}}$) are accurately measured by means of single and double Fabry-Perot etalons and with the use of electromagnetically enriched isotopes. The shifts between successive even isotopes are found to decrease with increasing neutron number in an irregular manner. Accurate values are obtained for the odd-even and odd-odd shifts in $\lambda $ 4416; this involved the study of the h.f.s. of the lines $\lambda $ 3250 and $\lambda $ 3535. Pronounced odd-even staggering is found. Some conclusions on the change of nuclear deformation with neutron number are drawn and possible connexions with shell structure discussed.