Abstract
We report the first calculation of the photodetachment cross section for the metastable, 1s2s2pPo4 state of He. Extensive configuration-interaction wave functions and the Stieltjes-moment-theory technique were used to determine the total cross section from threshold to 3.0 eV. The 1s2p2Pe4 state of He gives rise to a very large (∼ 24 × 1016 cm2) and narrow peak 10 meV above the 23Po threshold.