MEASUREMENT OF THE XUV PHOTOABSORPTION SPECTRA OF ATOMIC ZINC AND ITSIONS ZNN- N=1, 2, AND 3 IN THE REGION OF 3P-SUBSHELL EXCITATION( )

Photoabsorption studies, using the dual laser plasma technique, have b een initiated along the zinc isonuclear sequence as far as Zn3+ in the energy region corresponding to 3p-subshell electron excitation. For n eutral, singly and doubly ionized zinc the 3d-subshell remains closed and excitations of the type 3p-ns have been found to predominate. The symmetric nature of the resonance profiles is evidence of the weak int eraction of these discrete states with the underlying 3d epsilon l con tinua. The relatively large widths of the resonances can be interprete d as being mostly due to the nonradiative decay of the 3p core hole th rough both super and normal Coster-Kronig decay processes. The spectra l signature of the 'transition metal-like' Zn3+ 3p-3d resonance is dra matically different, the asymmetric nature of which reflects the incre ased interaction between direct 3d photoionization and the-discrete ex citation processes. The main resonances in the spectra of Zn+, Zn2+, a nd Zn3+ have been parametrized and compared with calculations based on both single-particle and collective models.