Statistics and characteristics of xuv transition arrays from laser-produced plasmas of the elements tin through iodine

Spectra of laser-produced plasmas of the elements from tin to iodine contain weak bands of quasicontinuum overlaid by weak emission lines in the 70–120-Å region. Multiconfiguration-Dirac-Fock calculations show that these features are consistent with theoretical spectra for 4d^N-4d^N-1(5f+6p) transitions in a number of adjacent ion stages which are predicted to produce unresolved transition arrays (UTA) in this spectral region. Moreover, the calculations predict a gradual decrease of 4d-5f oscillator strength with increasing ionization up to the eleventh spectrum where Jgf(4d-5f)≊0. However, inclusion of configuration interaction effects between the 4d⁹nf levels showed that 4d⁹4f and 4d⁹5f mixing shifts this minimum to the thirteenth spectrum. The theoretical data were then parametrized within the UTA formalism and the different order moments corresponding to weighted mean energy, variance, and skewness coefficient evaluated.