The 2p-subshell photoabsorption spectrum of Al+in a laser-produced plasma

The authors have recorded the time-resolved photoabsorption spectra of aluminium plasmas in the 50-200 AA wavelength range using the dual laser produced plasma technique (DLPP). Absorbing plasmas were generated by focusing the output from a pulsed dye or a Q-switched ruby laser onto an aluminium slab target. The continuum backlight was provided by irradiating a tantalum rod with the output from a time-synchronized Q-switched Nd-YAG laser. Some of the spectra were recorded with the aid of a toroidal mirror. By combining time and space resolution the authors have been able to isolate almost exclusively Al + and record its photoabsorption spectrum. They provide an analysis of 2p to nd, (n+1)s Rydbergs in Al + based on multiconfiguration ab initio atomic structure calculations and quantum defects for the higher members of each series. They have also observed and tentatively classified a number of members of the 2p 6 3s 2 to 2p 5 3s3p 2 doubly excited transition array.