Interpretation of a spectrum of laser irradiated strontium in the range 115-208 Å

Multicharged ions of strontium have been produced by laser irradiation (0.53 μm) of strontium targets with laser intensities of about 1014 W/cm2 on the target. Their spectrum has been observed with a crystal spectrograph in the range 4.5-7 A and with a grazing-incidence spectrograph from 115 to 208 A. Eight prominent lines previously identified as Sr XXVII and Sr XXVIII were used as internal standards for deriving wavelengths of about ninety lines from 115 to 208 A. Ab initio evaluations of energies and transition probabilities in Sr XXVII by the relativistic parametric potential method support the identification of the configurations 3s3p, 3p3d, 3s3d and 3p2 which are now almost complete. Some weaker lines are attributed to Al-like Sr XXVI and Ne-like Sr XXIX.