Anomalous<i>Z</i>dependence of a magnetic dipole transition in the Ti I isoelectronic sequence

Abstract

In isoelectronic sequences, transition wavelengths ordinarily move rapidly to shorter wavelengths as Z increases. However, it has been predicted that a particular sequence of magnetic dipole (M1) transition wavelengths for the Ti-like ions, ${\mathrm{Xe}}^{+32}$ through ${\mathrm{U}}^{+70}$, remain relatively constant in the 320--400-nm range. In the present paper we extend the experimental identifications of the Ti-like M1 transitions from Ba and Xe to Nd (${\mathrm{Nd}}^{+38}$) and Gd (${\mathrm{Gd}}^{+42}$) to verify this behavior. Using the newly acquired wavelengths to adjust atomic parameters, we have also calculated improved wavelengths for all such M1 transitions between Xe (Z=54) and Os (Z=76). \textcopyright{} 1996 The American Physical Society.