The excited4Poand4P states of lithium

Absolute term values of Li(1s2snp) 4 P o and (1s2pnp) 4 P states (n=3,4,5) and their corresponding transition probabilities for electric dipole decay are calculated by means of configuration interaction calculations approximately corrected for relativistic, radiative and mass polarisation effects. Only 1s2pnp to 1s2snp transitions (n=2,3,4,5) possess relatively high decay rates to be readily observed in the beam-foil source; however, the n=5 transition at lambda =5405.2(0.6) AA has not yet been detected. Unobserved weak and very weak lines are predicted. An earlier assignment of lambda =8504 AA to 1s2s3p is not confirmed ( lambda =8605.0(2.5) AA at very weak intensity but within the range of detectability). Comparison of theoretical E1 decay rates with experimental mean lifetimes suggests that autoionisation is by far the principal mode of decay for all these even-parity 4 P states except 1s2p 2 , thus explaining the scarce participation of 4 P o to or from 4 P transitions in Li quarter spectra.