Anomalous Z dependence of a magnetic dipole transition in the Ti I isoelectronic sequence

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, Xe+32 through 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 (Nd+38) and Gd (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).