Transitions and energy levels in Mg-like Ge XXI-Zr XXIX observed in laser-produced linear plasmas

Transitions in Ge XXI, Se XXIII, Sr XXVII, Y XXVIII, and Zr XXIX were identified in the extreme-ultraviolet spectra emitted from linear plasmas that were produced using line-focused laser beams. A grazing-incidence spectrograph viewed the plasma in the axial direction. The spectral lines were quite narrow owing to the reduced ion motion along the line of sight. Transitions of the type 3s2-3s3p, 3s3p-3p2, 3s3p-3s3d, 3p2-3p3d, 3s3d-3p3d, and 3p3d-3d2 were identified, and the wavelengths in the range 100-230 A were measured with an uncertainty of ±0.010 A. The energy levels were determined from a large number of combinations. Fitted energy levels are presented for all of the elements from Ga XX to Zr XXIX with an uncertainty smaller than 50 cm-1. (orig.)