Doubly Excited Resonances in the Photoionization Spectrum of Li$^{+}$: experiment and theory

Absolute cross-section measurements for resonant double photoexcitation of Li${^+}$ ions followed by subsequent autoionization have been performed in the photon energy range from 148 eV, just below the (2s2p, $_2$(0,1)$_2^+$) resonance to 198 eV (the region of the double ionization threshold) at high resolution. The measurements have been made using the photon-ion merged-beam endstation at the Advanced Light Source, Lawrence Berkeley National Laboratory. The absolute cross section measurements when compared with theoretical results from the R-matrix plus pseudo-state (RMPS) method show excellent agreement. Comparisons made between theory and experiment for the Auger resonance energies, autoionization linewidth ($\Gamma$) and the Fano line profile index $q$ for several members of the principal (2snp, $_2$(0,1)$_n^+$) and (3snp, $_3$(1,1)$_n^+$) Rydberg series found in the photoionization spectra for the $\rm ^1P^o$ symmetry show suitable accord. Further details will be presented at the meeting.