X-ray observations of 2l-nl′ transitions from Zr, Nb, Mo, and Pd in near-neonlike charge states

X-ray spectra of 2l-nl{'} transitions with 3{≤}n{≤}12 in the row-5 transition metals zirconium (Z=40), niobium (Z=41), molybdenum (Z=42), and palladium (Z=46) from charge states around neonlike have been observed from Alcator C-Mod plasmas. Accurate wavelengths (±{}0.2 m{}) have been determined by comparison with neighboring argon, chlorine, and sulfur lines with well-known wavelengths. Line identifications have been made by comparison to ab initio atomic structure calculations, using a fully relativistic, parametric potential code. For neonlike ions, calculated wavelengths and oscillator strengths are presented for 2p-nd transitions with n between 3 and 12. The magnitude of the configuration interaction between the (2p⁵{)}1/2$6${d}3/2$ J=1 level and the (2${p}⁵)3/27d5/2 J=1 levels has been measured as a function of energy-level spacing for successive-atomic-number neonlike ions, and the agreement with theory is good. Transitions in the 2p1/2-nd3/2 series in neonlike Mo³²⁺ with n{≥}13 are not observed; the upper levels lie above the first ionization potential of the neonlike ion and have a large branching ratio towards autoionization. Measured and calculated wavelengths and oscillator strengths of selected transitions in the aluminum-, magnesium-, sodium-, fluorine-, and oxygenlike isosequences are also presented. {} 1996 The American Physical Society.