Fine structure effect on the line shape of hydrogen-like ions

It is shown that allowance for the fine structure of a multi-charged hydrogen-like ion leads to a radical alternation of the line shape compared to the nonrelativistic analysis. The spectral function becomes nonsymmetric and narrow components appear which are due partly to the nonmonotonous variation of the terms. Detailed calculations are carried out for the 4 → 3 transition in hydrogen-like ions with Z=22.30 in a plasma with Ni ∼ 1017Z2 cm-3 and T ∼ Z2 eV