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 c ontain weak bands of quasicontinuum overlaid by weak emission lines in the 70-120-Angstrom region. Multiconfiguration-Dirac-Fock calculation s 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 dec rease of 4d-5f oscillator strength with increasing ionization up to th e eleventh spectrum where Sigma gf(4d-5f)approximate to 0. However, in clusion of configuration interaction effects between the 4d(9)nf level s showed that 4d(9)4f and 4d(9)5f mixing shifts this minimum to the th irteenth spectrum. The theoretical data were then parametrized within the UTA formalism and the different order moments corresponding to wei ghted mean energy, variance, and skewness coefficient evaluated.