Absorption oscillator strengths to autoionizing states in Li, N, and F and their isoelectronic sequences

Abstract

We have calculated the photoabsorption oscillator strengths of the one and two-electron transitions Li 1s22s2S → 2s22p2P0, NI 2s22p32P0 → 2s2p42D, NI 2s22p32D0 → 2s2p42D, and FI 2s22p52P0 → 2s2p62S, whose upper states are autoionizing, according to a new first order theory of oscillator strengths (FOTOS). These oscillator strengths are often very small and are sensitive to the details of electron–electron interactions. Also computed are the f values for ions in the N and F isoelectronic sequences. Comparison of our theory with three very recent beam-foil values in OII, FIII, and NeII shows excellent agreement.