Shortening of pulses emitted by a chemical DF–CO₂laser

Abstract

Absolute term values of L i ( l~2 s n p )~P " and ( 1~2 p n p )~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 ls2pnp-ls2snp 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 A = 5405.2(0.6) 8, has not yet been detected. Unobserved weak and very weak lines ((0.2) and 6469.8(0.8)A) are predicted. An earlier assignment of A = 8504 8, to ls2p3p+ ls2s4p is not confirmed (A = 8605.0(2.5) 8, at very weak intensity but within the range of detectability). Comparison of theoretical E l decay rates with experimental mean lifetimes suggests that autoionisation is by far the principal mode of decay for all these even-parity 4P states except ls2p2, thus explaining the scarce participation of 4~0 -4~ transitions in Li quartet spectra.