Observability of Hyperfine Structure and Lamb, Nuclear-Volume Shifts in1snl−1snl′Transitions of Heliumlike Ions

The hyperfine-structure widths of $1snl-1sn{l}^{\prime }$ transitions in heliumlike ions are estimated for $n=2, 3 \mathrm{and} Z$ up to 30. Relevant parameters such as spin-orbit and electrostatic parameters are also calculated on the basis of screened hydrogenic functions. It is found that the hyperfine-structure widths are greater than 10 Å at accessible visible wavelengths in some cases. Also, absolute wavelength shifts due to Lamb and nuclear-volume effects are of the order of several angstroms.