We have applied the methods of fast-ion-beam laser spectroscopy (FIBLAS) and laser-rf double resonance to study the 4$p^4$${(\mathrm{}}^3$P)4d ${\mathrm{}}^4$$D_{7/2}$→4$p^4$${(\mathrm{}}^3$P)5p ${\mathrm{}}^4$$D_{7/2}^o$ transition at 642.018 nm in ${}_{}{}^{83}{}_{}{}^{}\mathrm{i}\mathrm{i}$. The effective hyperfine constants of the 4d ${\mathrm{}}^4$$D_{7/2}$ state were measured by radiofrequency magnetic resonance, with the results (in MHz) A=-43.5132(3), B=-294.921(5), and C=-0.0030(6). The FIBLAS results for the 5p ${\mathrm{}}^4$$D_{7/2}^o$ effective hyperfine constants are (in MHz) A’=-145.29(7) and B’=536(2). .AE

• Received 30 September 1985

DOI:https://doi.org/10.1103/PhysRevA.33.2396