Single and double photoionization of lithium

The photoion Li2+/Li+ production cross section ratio of ground-state atomic lithium has been measured for photon energies ranging from 80 to 424 eV. T he absolute;cross sections for the Li2+ and Li+ yield an also derived. Ln t his energy region, the Li2+/Li+ ratio reaches a plateau of about 1.0% befor e reaching a maximum of about 4.5%, then decreases slowly. Good agreement i s found between the measured total photoionization cross sections of lithiu m and theoretical calculations. The Li2+/Li+ ratio is also compared to the He2+/He+ ratio from excited He(1s2s) for photon energies up to 70 eV above threshold. The branching ratio of Li2+ to total Li ion production is also c ompared to the single-ionization cross section of electron impact on Li+ io ns. [S1050-2947(99)03605-7].